fix: auto-recover from TDLib upload stalls by recreating client

When TDLib's event stream degrades, uploads complete (bytes sent) but
confirmations never arrive. Previously the worker retried 3x with the
same broken client, wasting 60+ min per archive and holding the mutex.

- Add UploadStallError class to distinguish stalls from other failures
- Reduce stall detection timeout from 5min to 3min (faster detection)
- Recreate TDLib client after consecutive upload stalls instead of
  retrying on the same degraded connection
- Add forceReleaseMutex() to prevent cascade failures when one account
  blocks others via stuck mutex after cycle timeout

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

worker/src/upload/channel.ts

@@ -7,6 +7,18 @@ import { withFloodWait, extractFloodWaitSeconds } from "../util/retry.js";
 
 const log = childLogger("upload");
 
+/**
+ * Custom error class to distinguish upload stalls from other errors.
+ * When consecutive stalls occur, the caller can use this signal to
+ * recreate the TDLib client (whose event stream may have degraded).
+ */
+export class UploadStallError extends Error {
+  constructor(message: string) {
+    super(message);
+    this.name = "UploadStallError";
+  }
+}
+
 export interface UploadResult {
   messageId: bigint;
   messageIds: bigint[];
@@ -109,13 +121,21 @@ async function sendWithRetry(
 
       // Stall or timeout — retry with a cooldown
       const errMsg = err instanceof Error ? err.message : "";
-      if ((errMsg.includes("stalled") || errMsg.includes("timed out")) && !isLastAttempt) {
-        log.warn(
-          { fileName, attempt: attempt + 1, maxRetries: MAX_UPLOAD_RETRIES },
-          "Upload stalled/timed out — retrying"
+      if (errMsg.includes("stalled") || errMsg.includes("timed out")) {
+        if (!isLastAttempt) {
+          log.warn(
+            { fileName, attempt: attempt + 1, maxRetries: MAX_UPLOAD_RETRIES },
+            "Upload stalled/timed out — retrying"
+          );
+          await sleep(10_000);
+          continue;
+        }
+        // All stall retries exhausted — throw UploadStallError so the caller
+        // knows the TDLib client's event stream is likely degraded and can
+        // recreate the client before continuing.
+        throw new UploadStallError(
+          `Upload stalled after ${MAX_UPLOAD_RETRIES} retries for ${fileName}`
         );
-        await sleep(10_000);
-        continue;
       }
 
       throw err;
@@ -166,8 +186,10 @@ async function sendAndWaitForUpload(
       }
     }, timeoutMs);
 
-    // Stall detection: no progress for 5 minutes after upload started → reject
-    const STALL_TIMEOUT_MS = 5 * 60_000;
+    // Stall detection: no progress for 3 minutes after upload started → reject
+    // (reduced from 5min — once data is fully sent, confirmation should arrive quickly;
+    //  a 3min silence strongly indicates a degraded TDLib event stream)
+    const STALL_TIMEOUT_MS = 3 * 60_000;
     const stallChecker = setInterval(() => {
       if (settled || !uploadStarted) return;
       const stallMs = Date.now() - lastProgressTime;