fix: review skipped silently when task diff exceeds 1MB maxBuffer

getCommitRangeDiff and getLatestCommitDiff had maxBuffer set to 1MB.
When a task produced a larger diff (common for 10+ minute tasks),
execSync threw, the catch block returned null, and the review loop
broke immediately with no message — reviews were silently skipped for
larger tasks while smaller tasks reviewed fine.

- Increase maxBuffer to 10MB in both functions (the review prompt
  builder already truncates to MAX_DIFF_BYTES = 50KB before sending
  to the model, so the full diff in memory is fine)
- Add a diagnostic sendChatMessage when the review loop is skipped
  (baseRef undefined or no diff), so silent skips are visible

src/executor.ts

@@ -877,7 +877,15 @@ async function executeTask(
 							const reviewInfo = baseRef
 								? getCommitRangeDiff(worktreeDir, baseRef)
 								: null;
-							if (!reviewInfo || !reviewInfo.diff) break; // nothing to review
+							if (!reviewInfo || !reviewInfo.diff) {
+								const reason = !baseRef
+									? "could not capture base ref before execution"
+									: "no changes found between base and HEAD";
+								sendChatMessage?.(
+									`~ review for ${task.id} · ${task.title} — skipping review (${reason})`,
+								);
+								break;
+							}
 
 							const reviewPrompt = buildReviewPrompt(
 								task,