fix: pin status posts, staleness filter, correct transcript parsing

- Auto-pin status posts on creation, unpin on session completion
- Skip stale sessions (>5min since last transcript write)
- Parse OpenClaw JSONL format (type:message with nested role/content)
- Handle timestamp-prefixed transcript filenames

src/watcher-manager.js

@@ -331,6 +331,14 @@ async function startDaemon() {
       logger.error({ sessionKey, err }, 'Failed to update final status');
     }
 
+    // Unpin the status post when session is done
+    try {
+      await sharedStatusBox._apiCall('POST', `/api/v4/posts/${box.postId}/unpin`, null);
+      logger.debug({ sessionKey, postId: box.postId }, 'Status post unpinned');
+    } catch (unpinErr) {
+      logger.warn({ sessionKey, err: unpinErr }, 'Failed to unpin status post');
+    }
+
     // Clean up
     activeBoxes.delete(sessionKey);
     watcher.removeSession(sessionKey);