Fix duplicate-post and timeout bugs in TG/MAX posting pipeline

- Stop blindly retrying send_photo/send_video/send_media_group and MAX
  send_message on ambiguous network timeouts - a timeout doesn't prove
  the message wasn't delivered, and retrying risked posting duplicates
  (observed live: a video posted 3-5x after repeated timeout retries).
- Raise/rework timeouts that were too short for real large-file transfer
  speeds: TG media upload timeout, and yt-dlp download now uses stall
  detection (killed only on true silence) instead of a flat ceiling that
  was cutting off legitimately slow-but-successful video downloads.
- Fix sendRichMessage: ok=true with an unparseable message_id no longer
  triggers a fallback send (Telegram already created the message).
- MAX: videos over the documented 250MB cap are now sent as a "watch via
  link" note instead of silently failing the upload.
- Add PRAGMA busy_timeout to all DB connections.
- Remove unused MAX_MEDIA_CHANNEL_ID (MAX's /uploads returns a portable
  token directly, no staging channel needed, unlike Telegram).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/database.py

@@ -2,8 +2,8 @@ from __future__ import annotations
 from loguru import logger
 
 import json
-from datetime import datetime
-from typing import Any, Optional
+from contextlib import asynccontextmanager
+from typing import Any, AsyncIterator, Optional
 import aiosqlite
 try:
     from .config import settings
@@ -11,13 +11,26 @@ except (ImportError, ValueError):
     from config import settings
 
 
+# Each method opens its own short-lived connection (no pooling). busy_timeout
+# means a second connection opened concurrently (e.g. inspecting the DB by
+# hand with sqlite3 while the service runs) waits instead of immediately
+# failing with "database is locked".
+_BUSY_TIMEOUT_MS = 5000
+
+
 class Database:
     def __init__(self, db_path: Optional[str] = None) -> None:
         self.db_path = str(settings.db_path if db_path is None else db_path)
 
+    @asynccontextmanager
+    async def _connect(self) -> AsyncIterator[aiosqlite.Connection]:
+        async with aiosqlite.connect(self.db_path) as db:
+            await db.execute(f"PRAGMA busy_timeout = {_BUSY_TIMEOUT_MS};")
+            yield db
+
     async def init(self) -> None:
         logger.info("Initializing database at {}", self.db_path)
-        async with aiosqlite.connect(self.db_path) as db:
+        async with self._connect() as db:
             await db.execute("PRAGMA journal_mode=WAL;")
             await db.execute(
                 """
@@ -58,7 +71,7 @@ class Database:
             await db.commit()
 
     async def has_any_posts(self, owner_id: int) -> bool:
-        async with aiosqlite.connect(self.db_path) as db:
+        async with self._connect() as db:
             cursor = await db.execute(
                 "SELECT 1 FROM posts WHERE vk_owner_id = ? LIMIT 1",
                 (owner_id,),
@@ -76,7 +89,7 @@ class Database:
         reason: str = "bootstrap_initial_skip",
     ) -> None:
         raw_json = json.dumps(raw_data, ensure_ascii=False)
-        async with aiosqlite.connect(self.db_path) as db:
+        async with self._connect() as db:
             await db.execute(
                 """
                 INSERT INTO posts (vk_owner_id, vk_post_id, posted_at, text, raw_json, tg_status, max_status, tg_error, max_error)
@@ -90,23 +103,22 @@ class Database:
             await db.commit()
 
     async def is_post_processed(self, owner_id: int, post_id: int) -> bool:
-        async with aiosqlite.connect(self.db_path) as db:
+        async with self._connect() as db:
             db.row_factory = aiosqlite.Row
             cursor = await db.execute(
-                "SELECT id, tg_status, max_status FROM posts WHERE vk_owner_id = ? AND vk_post_id = ?",
+                "SELECT tg_status, max_status FROM posts WHERE vk_owner_id = ? AND vk_post_id = ?",
                 (owner_id, post_id),
             )
             row = await cursor.fetchone()
             if not row:
                 return False
-            # If already published on both or marked skipped, it's processed
             return bool(
                 row["tg_status"] in ("published", "skipped")
                 and row["max_status"] in ("published", "skipped")
             )
 
     async def get_post(self, owner_id: int, post_id: int) -> Optional[dict[str, Any]]:
-        async with aiosqlite.connect(self.db_path) as db:
+        async with self._connect() as db:
             db.row_factory = aiosqlite.Row
             cursor = await db.execute(
                 "SELECT * FROM posts WHERE vk_owner_id = ? AND vk_post_id = ?",
@@ -124,7 +136,7 @@ class Database:
         raw_data: dict[str, Any],
     ) -> int:
         raw_json = json.dumps(raw_data, ensure_ascii=False)
-        async with aiosqlite.connect(self.db_path) as db:
+        async with self._connect() as db:
             cursor = await db.execute(
                 """
                 INSERT INTO posts (vk_owner_id, vk_post_id, posted_at, text, raw_json)
@@ -149,7 +161,7 @@ class Database:
         error: Optional[str] = None,
     ) -> None:
         msg_str = ",".join(str(m) for m in message_ids) if message_ids else None
-        async with aiosqlite.connect(self.db_path) as db:
+        async with self._connect() as db:
             await db.execute(
                 """
                 UPDATE posts
@@ -173,7 +185,7 @@ class Database:
         error: Optional[str] = None,
     ) -> None:
         msg_str = ",".join(message_ids) if message_ids else None
-        async with aiosqlite.connect(self.db_path) as db:
+        async with self._connect() as db:
             await db.execute(
                 """
                 UPDATE posts
@@ -196,7 +208,7 @@ class Database:
         status: str = "ok",
         error: Optional[str] = None,
     ) -> None:
-        async with aiosqlite.connect(self.db_path) as db:
+        async with self._connect() as db:
             await db.execute(
                 """
                 INSERT INTO publication_runs (found_count, published_tg_count, published_max_count, status, error)