feat(KB-617): add Changes tab to task detail modal with file diffs

- Add modifiedFiles and baseCommitSha fields to task schema for tracking changes
- Capture list of modified files during task execution in the executor
- Add GET /tasks/:id/diff API endpoint to retrieve file list and patches
- Create TaskChangesTab component with expandable file diffs
- Integrate Changes tab into TaskDetailModal for in-progress, in-review, and done tasks
- Add CSS styles for diff viewer with syntax highlighting
- Update API client with fetchTaskDiff function and Project Management types

packages/cli/src/commands/task.ts

@@ -1416,7 +1416,7 @@ export async function runTaskPlan(initialPlanArg?: string, yesFlag = false): Pro
 
       try {
         showThinking();
-        result = await submitResponse(sessionId, response) as typeof result;
+        result = await submitResponse(sessionId, response as Record<string, unknown>) as typeof result;
         clearThinking();
       } catch (err) {
         clearThinking();