fix(stability): declare pytest-asyncio, bound /raw_json RPC, assert FloodWait backoff, dedupe gate+timeout (review round 1)

F1 [WARNING] pytest-asyncio was not declared, so the 6 new async stage-1 tests
ERROR on a clean checkout (async def not natively supported) — zero regression
protection, masked by a globally-installed plugin. Added pytest-asyncio to
requirements.txt + asyncio_mode=auto to tests/pytest.ini. Verified on a fresh venv
from requirements alone: the tests collect and run (180 passed).

F2 [WARNING] The /raw_json endpoint's get_messages was the one remaining live RPC
without a timeout, violating the stage-1 DoD ('every Telegram RPC is bounded').
Wrapped it in asyncio.wait_for(..., 30) mirroring PostParser.get_post. (It is not
under the tg_rpc gate, so its blast radius was one request, not the app.)

F3 [WARNING] The worker test globally no-op'd asyncio.sleep, so the dedicated
except FloodWait branch was indistinguishable from the generic handler — deleting
it kept the test green. The sleep stub now records delays and the test asserts the
FloodWait backoff of 6 (=min(1+5,900)), distinct from the success path's 2.

F5 [low] The tricky 'gate outside, timeout inside' nesting was open-coded at 3
sites (each re-deriving the invariant). Extracted tg_rpc_bounded(timeout) into
tg_throttle (using asyncio.timeout()); the 3 sites now use it, so a future call
site cannot silently wrap the gate entry and reopen the hang-under-backpressure.

F4 [low] Documented TG_RPC_TIMEOUT in the dockercompose.yml environment block
next to the other TG_RPC_* knobs.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

api_server.py

@@ -917,7 +917,12 @@ async def get_raw_post_json(channel: str, post_id: int, request: Request, token:
         if isinstance(channel, str) and channel.startswith('-100'):
             channel_id = int(channel)
             
-        message = await client.client.get_messages(channel_id, post_id)
+        # Bound the RPC (stage-1 DoD: every Telegram RPC has a timeout). This
+        # endpoint is not under the tg_rpc gate, so a hang here only blocks this
+        # one request, but leaving it unbounded still violates the invariant.
+        message = await asyncio.wait_for(
+            client.client.get_messages(channel_id, post_id), timeout=30
+        )
         if not message:
             raise HTTPException(status_code=404, detail="Post not found")