Add file changes panel per conversation

[saneroen]

Closes: #11493

Description

This PR adds a per-conversation file diff feature: for each task, users can see a single list of all files changed in that conversation and expand to view the diff for each file (similar to Cursor's file diff per chat).

Implementation:

• Derivation (webview-ui/src/components/chat/utils/fileChangesFromMessages.ts): New utility that, given clineMessages, returns a list of file-change entries (path, diff, diffStats). It considers both type === "say" + say === "tool" and type === "ask" + ask === "tool" (file edits are stored as ask messages after approval). Partial messages are skipped. Single-file tools (editedExistingFile, appliedDiff, newFileCreated, etc.) and batchDiffs are supported.
• UI (webview-ui/src/components/chat/FileChangesPanel.tsx): New collapsible panel that shows "X file(s) changed in this conversation" and, when expanded, one row per file (grouped by path; multiple edits to the same file are merged) with an expandable diff via existing CodeAccordian. Renders only when there is at least one file change. Placed below the scrollable chat and above the action buttons.
• Integration (webview-ui/src/components/chat/ChatView.tsx): Renders <FileChangesPanel clineMessages={messages} /> in the task view.
• i18n: Added fileChangesInConversation.header with {{count}} in en, de, and fr chat locales.
• Mark tool-approval asks as isAnswered when the user (or auto-approval) approves, and in the webview only include ask "tool" file edits where msg.isAnswered === true, so the file-changes panel shows only approved diffs.

No new persistence or extension API; all data is derived from existing task UI messages.

Test Procedure

1. Build & run: pnpm run vsix (or run from workspace with F5).
2. With file edits: Start a task, have the agent create or edit a file, approve the change. In the Chat tab, scroll to the bottom: the "X file(s) changed in this conversation" row appears below the messages. Expand it, then expand a file row to see the diff.
3. No file edits: Start a task that only reads files or runs commands. The file changes section does not appear.
4. Multiple files: Task that edits several files (or same file twice) shows all in the panel, grouped by path.
5. Switch tasks: Open History, switch to another task that had edits; file changes panel reflects that task's edits.

Pre-Submission Checklist

• Issue Linked: This PR is linked to an approved GitHub Issue (see "Related GitHub Issue" above).
• Scope: My changes are focused on the linked issue (one major feature/fix per PR).
• Self-Review: I have performed a thorough self-review of my code.
• Testing: Unit tests live in webview-ui/src/__tests__/
• Documentation Impact: No user-facing docs changes required for this feature.
• Contribution Guidelines: I have read and agree to the Contributor Guidelines.

Screenshots / Videos

Documentation Updates

• No documentation updates are required.
• Yes, documentation updates are required. (Describe or link.)

Additional Notes

• Panel returns null when there are no file changes, so no empty section is shown.
• Reuses CodeAccordian, parseUnifiedDiff, and existing diff styling for consistency with inline tool blocks.

Get in Touch

Discord: santy2509

Start a new Roo Code Cloud session on this branch

[roomote]

Rooviewer   See task

All four previously flagged issues have been resolved in this commit. No new issues found.

• Missing i18n translation key fileChangesInConversation.header -- now added to all 18 locale files
• Missing ChatView.tsx integration -- FileChangesPanel is now imported and rendered
• FILE_EDIT_TOOLS contains invalid tool names -- trimmed to the three valid ClineSayTool values
• expandedPaths state not reset on task switch -- useEffect now resets on clineMessages change

Previous reviews

• 66207f8: Review #1
• e416459: Review #2

_{Mention @roomote in a comment to request specific changes to this pull request or fix all unresolved issues.}