Fix worker getting stuck during sync: add timeouts, stuck detection, and safety limits

- Add invokeWithTimeout wrapper for TDLib API calls (2min timeout per call)
- Add stuck detection to getChannelMessages: break if from_message_id doesn't advance
- Add stuck detection to getTopicMessages: same protection for topic scanning
- Add stuck detection to getForumTopicList: break if pagination offsets don't advance
- Add max page limit (5000) to all scanning loops to prevent infinite pagination
- Add mutex wait timeout (30min) to prevent indefinite blocking when holder hangs
- Add cycle timeout (4h default, configurable via WORKER_CYCLE_TIMEOUT_MINUTES)
- Fix end-of-page detection to use actual limit value instead of hardcoded 100

Co-authored-by: xCyanGrizzly <53275238+xCyanGrizzly@users.noreply.github.com>

worker/dist/archive/split.d.ts

@@ -0,0 +1,11 @@
+/**
+ * Split a file into ≤2GB parts using byte-level splitting.
+ * Returns paths to the split parts. If the file is already ≤2GB, returns the original path.
+ */
+export declare function byteLevelSplit(filePath: string): Promise<string[]>;
+/**
+ * Concatenate multiple files into a single output file by streaming
+ * each input sequentially. Used for repacking multipart archives
+ * that have oversized parts (>2GB) before re-splitting.
+ */
+export declare function concatenateFiles(inputPaths: string[], outputPath: string): Promise<void>;