fix(config): remove retired codebase search schema

[johnnyeric]

Summary

Remove the retired experimental.codebase_search property from the Kilo Cloud config JSON Schema mirror after its removal in Kilo Code PR #13084.

Update the focused schema merge test to ensure the retired key remains absent while the surviving Kilo experimental keys and upstream keys are preserved.

Verification

• No manual testing required; this is a non-UI JSON Schema metadata cleanup.
• pnpm --filter web test -- --runInBand src/tests/cli-config-schema.test.ts — 11 tests passed
• Oxlint on both changed files
• Oxfmt check on both changed files
• pnpm --filter web typecheck
• git diff --check

Visual Changes

N/A

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (2 files)

• apps/web/src/app/config.json/extras.ts
• apps/web/src/tests/cli-config-schema.test.ts

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_{Reviewed by kimi-k3 · Input: 67.9K · Output: 3.3K · Cached: 273.4K}

_{Review guidance: REVIEW.md from base branch main}