Issue for this PR

Addresses #37891

Type of change

• New feature

What does this PR do?

In assistant messages, file paths in inline code (e.g. packages/app/src/app.tsx:301) are highlighted but clicking them does nothing, so they end up copy-pasted. This makes them clickable: clicking opens the file in the existing review panel and highlights the referenced line when the path ends in :line.

Kept the scope small and contained to the web/desktop renderer:

• a delegated click handler on path-kind inline code in the markdown component (same pattern as the existing copy-button handler there)
• an optional onOpenFile callback on the session data context, implemented in the session page using the same openReviewFile flow the file tree already uses
• a small parser for path, path:line, and path:line:col (handles Windows drive paths)
• pointer cursor + hover underline, only when the callback is present

URLs, fenced code blocks, and the TUI are untouched.

How did you verify your code works?

• unit tests for the parser (10 cases: Windows paths, :line:col, invalid line numbers, URLs, whitespace)
• bun test in packages/session-ui: 93 pass; typecheck clean in session-ui and app
• manually in the desktop dev app: clicking a backticked path opens the review panel at the referenced line; plain-text paths and other code spans behave exactly as before

Opening as draft per the contributing guide since this is a UI feature — happy to reshape the approach after design review.

Screenshots / recordings

Attaching in a follow-up comment (recording of click → review panel opening at the line).

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR