Pitch

Tool errors, stack traces, sandbox denials, and `grep_files` results constantly include `crates/tui/src/foo.rs:42:7` references. Right now they're plain text — copy, paste into another terminal, open manually. Make them clickable, like opencode/Cursor's terminal: click the path, it opens in $EDITOR (or jumps to that location in the user's IDE via a registered URL handler).

Implementation sketch

1. Pattern-match `path/to/file.:(:)?` in transcript spans during the existing wrap pass.
2. Wrap matches in a span with a hyperlink modifier (ratatui `Modifier::HYPERLINK` or a custom click-target tag).
3. Register a mouse-click handler that resolves the path against `app.workspace` and either:
   • emits OSC-8 hyperlink escape so the terminal handles open natively (the cleanest cross-platform answer, supported by iTerm2 / Wezterm / Kitty / Windows Terminal); or
   • shells out to `$EDITOR + ` directly.
4. Visual cue: underline + sky-blue when the cursor hovers (only when mouse capture is on).

Acceptance

• Tool output containing `path:line` is rendered as a clickable hyperlink.
• Click in iTerm2 / Wezterm / Windows Terminal opens the file at the right line.
• No regression for users who don't have mouse capture enabled.
• Doesn't break copy-paste of the raw path.

Prior art

Closed #323 covered the same surface area; reopening as a v0.8.6 deliverable since this lands well inside the polish window.