* fix: improve plan comment formatting to match code review style
- Update formatPlanCommentsAsMarkdown to use code blocks and blockquotes
- Remove duplicate header in chat-input-area.tsx
- Update buildDocumentContext to use consistent formatting
- Fixes duplicate '### Plan Comments' headers and extra separators
* fix: add tests and fix multiline blockquote handling
- Add format.test.ts for formatPlanCommentsAsMarkdown and related functions
- Fix multiline comment text to properly prefix each line with >
- Addresses review feedback about missing tests and broken blockquotes
* fix: export and reuse toBlockquote helper to avoid duplication
* fix: update E2E test to match new plan comment format
The test was expecting 'Comment 1:' which was the old bullet-style format.
Now looks for 'Plan Comments' header instead.
João Salavisa