docs: update Hono quickstart to beta SDK API

[tusharpandey13]

Summary

• Updates the Hono webapp quickstart (/main/docs/quickstart/webapp/hono/index.mdx) to reflect the @auth0/auth0-hono@1.0.0 beta SDK API
• Fixes 6 API corrections: auth() → auth0(), Auth0Exception → Auth0Error, BASE_URL → APP_BASE_URL, async getSession() → sync c.var.auth0.user/.session, removes explicit config in favor of zero-config pattern
• Adds AI assistant accordion with agent skills integration (matches Next.js quickstart pattern)
• Fixes Windows CLI command: AUTH0_SECRET → AUTH0_SESSION_ENCRYPTION_KEY

Changes

• New section: AI accordion for agent skills integration (auth0-hono skill)
• Step 4 code block: Complete replacement with zero-config auth0() middleware, sync user access via c.var.auth0.user, and Auth0Error error handling
• Environment variables: BASE_URL → APP_BASE_URL across CLI (Mac + Windows), Dashboard .env, and Troubleshooting
• Troubleshooting/Best Practices/Advanced Usage: Updated all references to new API names

Test plan

• Run mint dev in main/ and verify Hono quickstart renders correctly
• Verify AI accordion displays with correct install command and prompt
• Verify Step 4 code block shows zero-config auth0() pattern
• Verify all .env examples use APP_BASE_URL
• Verify no references to old API (auth(, Auth0Exception, BASE_URL, auth0Client) remain
• Check mint broken-links passes