diff --git a/.github/dependabot.yml b/.github/dependabot.yml
new file mode 100644
index 0000000..0bba0b3
--- /dev/null
+++ b/.github/dependabot.yml
@@ -0,0 +1,21 @@
+version: 2
+updates:
+  - package-ecosystem: github-actions
+    directory: /
+    schedule:
+      interval: weekly
+    commit-message:
+      prefix: ci
+    labels:
+      - dependencies
+      - github-actions
+
+  - package-ecosystem: bundler
+    directory: /
+    schedule:
+      interval: weekly
+    commit-message:
+      prefix: deps
+    labels:
+      - dependencies
+      - ruby
diff --git a/.github/workflows/github-pages.yml b/.github/workflows/github-pages.yml
index dc5cea8..9822ed6 100644
--- a/.github/workflows/github-pages.yml
+++ b/.github/workflows/github-pages.yml
@@ -13,24 +13,24 @@ on:
 jobs:
   github-pages:
     runs-on: ubuntu-latest
-    container: ruby:3.2.2-bookworm
+    container: ruby:3.4.9-bookworm
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions/cache@v1
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+      - uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
         with:
           path: vendor/bundle
-          key: ${{ runner.os }}-gems-${{ hashFiles('**/Gemfile.lock') }}
+          key: ${{ runner.os }}-gems-${{ hashFiles('**/Gemfile.lock', '.ruby-version') }}
 
       - name: Install Ruby dependencies.
         run: |
           gem install bundler
-          bundle install --path vendor/bundle 
+          bundle install --path vendor/bundle
 
       - name: Build static site with Jekyll.
         run: bundle exec jekyll build
 
       - name: Deploy static site to gh-pages branch.
-        uses: peaceiris/actions-gh-pages@v3
+        uses: peaceiris/actions-gh-pages@4f9cc6602d3f66b9c108549d475ec49e8ef4d45e # v4.0.0
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
           publish_dir: ./_site
diff --git a/.github/workflows/pr-build-test.yml b/.github/workflows/pr-build-test.yml
new file mode 100644
index 0000000..7e9a046
--- /dev/null
+++ b/.github/workflows/pr-build-test.yml
@@ -0,0 +1,34 @@
+name: PR build test
+
+on:
+  pull_request:
+    paths:
+      - '.ruby-version'
+      - 'Gemfile'
+      - 'Gemfile.lock'
+      - '_config.yml'
+      - '_data/**'
+      - '_includes/**'
+      - '_layouts/**'
+      - '_plugins/**'
+      - '.github/workflows/pr-build-test.yml'
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    container: ruby:3.4.9-bookworm
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+
+      - uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
+        with:
+          path: vendor/bundle
+          key: ${{ runner.os }}-gems-${{ hashFiles('**/Gemfile.lock', '.ruby-version') }}
+
+      - name: Install Ruby dependencies.
+        run: |
+          gem install bundler
+          bundle install --path vendor/bundle
+
+      - name: Build static site with Jekyll.
+        run: bundle exec jekyll build
diff --git a/.github/workflows/pr-markdown-lint.yml b/.github/workflows/pr-markdown-lint.yml
new file mode 100644
index 0000000..75c4730
--- /dev/null
+++ b/.github/workflows/pr-markdown-lint.yml
@@ -0,0 +1,36 @@
+name: PR markdown lint
+
+on:
+  pull_request:
+    paths:
+      - '**/*.md'
+      - '.markdownlint-cli2.yaml'
+      - '.github/workflows/pr-markdown-lint.yml'
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          fetch-depth: 0
+
+      - uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # v6.4.0
+        with:
+          node-version: '24'
+
+      - name: Install markdownlint-cli2
+        run: npm install -g markdownlint-cli2@0.22.1
+
+      - name: Lint changed Markdown files
+        env:
+          BASE_SHA: ${{ github.event.pull_request.base.sha }}
+        run: |
+          files=$(git diff --name-only --diff-filter=d "$BASE_SHA"...HEAD -- '*.md')
+          if [ -z "$files" ]; then
+            echo "No changed Markdown files to lint."
+            exit 0
+          fi
+          echo "Linting:"
+          echo "$files"
+          echo "$files" | xargs -d '\n' -r markdownlint-cli2
diff --git a/.markdownlint-cli2.yaml b/.markdownlint-cli2.yaml
new file mode 100644
index 0000000..795addd
--- /dev/null
+++ b/.markdownlint-cli2.yaml
@@ -0,0 +1,10 @@
+# Rules: https://github.com/DavidAnson/markdownlint/blob/main/doc/Rules.md
+config:
+  default: true
+  MD013: false  # line-length — too disruptive for prose content
+  MD033: false  # no-inline-html — Jekyll posts frequently embed raw HTML
+
+ignores:
+  - 'vendor/**'
+  - '_site/**'
+  - 'node_modules/**'
diff --git a/.ruby-version b/.ruby-version
index be94e6f..7bcbb38 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-3.2.2
+3.4.9
diff --git a/Gemfile.lock b/Gemfile.lock
index 5348919..6b87d2f 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,31 +1,64 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    addressable (2.8.5)
-      public_suffix (>= 2.0.2, < 6.0)
+    addressable (2.9.0)
+      public_suffix (>= 2.0.2, < 8.0)
+    base64 (0.3.0)
+    bigdecimal (4.1.2)
     colorator (1.1.0)
-    concurrent-ruby (1.2.2)
+    concurrent-ruby (1.3.6)
+    csv (3.3.5)
     em-websocket (0.5.3)
       eventmachine (>= 0.12.9)
       http_parser.rb (~> 0)
     eventmachine (1.2.7)
-    ffi (1.16.2)
+    ffi (1.17.4-aarch64-linux-gnu)
+    ffi (1.17.4-aarch64-linux-musl)
+    ffi (1.17.4-arm-linux-gnu)
+    ffi (1.17.4-arm-linux-musl)
+    ffi (1.17.4-arm64-darwin)
+    ffi (1.17.4-x86_64-darwin)
+    ffi (1.17.4-x86_64-linux-gnu)
+    ffi (1.17.4-x86_64-linux-musl)
     forwardable-extended (2.6.0)
-    google-protobuf (3.24.3)
-    http_parser.rb (0.8.0)
-    i18n (1.14.1)
+    google-protobuf (4.34.1)
+      bigdecimal
+      rake (~> 13.3)
+    google-protobuf (4.34.1-aarch64-linux-gnu)
+      bigdecimal
+      rake (~> 13.3)
+    google-protobuf (4.34.1-aarch64-linux-musl)
+      bigdecimal
+      rake (~> 13.3)
+    google-protobuf (4.34.1-arm64-darwin)
+      bigdecimal
+      rake (~> 13.3)
+    google-protobuf (4.34.1-x86_64-darwin)
+      bigdecimal
+      rake (~> 13.3)
+    google-protobuf (4.34.1-x86_64-linux-gnu)
+      bigdecimal
+      rake (~> 13.3)
+    google-protobuf (4.34.1-x86_64-linux-musl)
+      bigdecimal
+      rake (~> 13.3)
+    http_parser.rb (0.8.1)
+    i18n (1.14.8)
       concurrent-ruby (~> 1.0)
-    jekyll (4.3.2)
+    jekyll (4.4.1)
       addressable (~> 2.4)
+      base64 (~> 0.2)
       colorator (~> 1.0)
+      csv (~> 3.0)
       em-websocket (~> 0.5)
       i18n (~> 1.0)
       jekyll-sass-converter (>= 2.0, < 4.0)
       jekyll-watch (~> 2.0)
+      json (~> 2.6)
       kramdown (~> 2.3, >= 2.3.1)
       kramdown-parser-gfm (~> 1.0)
       liquid (~> 4.0)
-      mercenary (>= 0.3.6, < 0.5)
+      mercenary (~> 0.3, >= 0.3.6)
       pathutil (~> 0.9)
       rouge (>= 3.0, < 5.0)
       safe_yaml (~> 1.0)
@@ -34,47 +67,84 @@ GEM
     jekyll-paginate (1.1.0)
     jekyll-redirect-from (0.16.0)
       jekyll (>= 3.3, < 5.0)
-    jekyll-sass-converter (3.0.0)
-      sass-embedded (~> 1.54)
+    jekyll-sass-converter (3.1.0)
+      sass-embedded (~> 1.75)
     jekyll-watch (2.2.1)
       listen (~> 3.0)
     jekyll_html_truncatewords (0.1.2)
       liquid
       nokogiri
-    kramdown (2.4.0)
-      rexml
+    json (2.19.4)
+    kramdown (2.5.2)
+      rexml (>= 3.4.4)
     kramdown-parser-gfm (1.1.0)
       kramdown (~> 2.0)
     liquid (4.0.4)
-    listen (3.8.0)
+    listen (3.10.0)
+      logger
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
+    logger (1.7.0)
     mercenary (0.4.0)
-    mini_portile2 (2.8.4)
-    nokogiri (1.15.4)
-      mini_portile2 (~> 2.8.2)
+    nokogiri (1.19.2-aarch64-linux-gnu)
+      racc (~> 1.4)
+    nokogiri (1.19.2-aarch64-linux-musl)
+      racc (~> 1.4)
+    nokogiri (1.19.2-arm-linux-gnu)
+      racc (~> 1.4)
+    nokogiri (1.19.2-arm-linux-musl)
+      racc (~> 1.4)
+    nokogiri (1.19.2-arm64-darwin)
+      racc (~> 1.4)
+    nokogiri (1.19.2-x86_64-darwin)
+      racc (~> 1.4)
+    nokogiri (1.19.2-x86_64-linux-gnu)
+      racc (~> 1.4)
+    nokogiri (1.19.2-x86_64-linux-musl)
       racc (~> 1.4)
     pathutil (0.16.2)
       forwardable-extended (~> 2.6)
-    public_suffix (5.0.3)
-    racc (1.7.1)
-    rake (13.0.6)
+    public_suffix (7.0.5)
+    racc (1.8.1)
+    rake (13.4.2)
     rb-fsevent (0.11.2)
-    rb-inotify (0.10.1)
+    rb-inotify (0.11.1)
       ffi (~> 1.0)
-    rexml (3.2.6)
-    rouge (4.1.3)
+    rexml (3.4.4)
+    rouge (4.7.0)
     safe_yaml (1.0.5)
-    sass-embedded (1.68.0)
-      google-protobuf (~> 3.23)
-      rake (>= 13.0.0)
+    sass-embedded (1.99.0-aarch64-linux-gnu)
+      google-protobuf (~> 4.31)
+    sass-embedded (1.99.0-aarch64-linux-musl)
+      google-protobuf (~> 4.31)
+    sass-embedded (1.99.0-arm-linux-gnueabihf)
+      google-protobuf (~> 4.31)
+    sass-embedded (1.99.0-arm-linux-musleabihf)
+      google-protobuf (~> 4.31)
+    sass-embedded (1.99.0-arm64-darwin)
+      google-protobuf (~> 4.31)
+    sass-embedded (1.99.0-x86_64-darwin)
+      google-protobuf (~> 4.31)
+    sass-embedded (1.99.0-x86_64-linux-gnu)
+      google-protobuf (~> 4.31)
+    sass-embedded (1.99.0-x86_64-linux-musl)
+      google-protobuf (~> 4.31)
     terminal-table (3.0.2)
       unicode-display_width (>= 1.1.1, < 3)
-    unicode-display_width (2.5.0)
-    webrick (1.8.1)
+    unicode-display_width (2.6.0)
+    webrick (1.9.2)
 
 PLATFORMS
-  ruby
+  aarch64-linux-gnu
+  aarch64-linux-musl
+  arm-linux-gnu
+  arm-linux-gnueabihf
+  arm-linux-musl
+  arm-linux-musleabihf
+  arm64-darwin
+  x86_64-darwin
+  x86_64-linux-gnu
+  x86_64-linux-musl
 
 DEPENDENCIES
   jekyll (~> 4.1)
@@ -84,4 +154,4 @@ DEPENDENCIES
   webrick (~> 1.7)
 
 BUNDLED WITH
-   2.2.22
+   2.6.9