fix: never swallow task exceptions - diagnose WHY the bot died

The restart-loop with only 'Starting discord bot' in the logs was caused by
gather(return_exceptions=True) eating the client.start() exception: a failed
login looked like a clean exit and docker just restarted the container.

bot.py:
- _run_bot: catch discord.LoginFailure / PrivilegedIntentsRequired with
  CRITICAL messages telling exactly what to fix (token entry / Developer
  Portal intents), full traceback for anything else, then re-raise
- main() returns an exit code; every task exception is re-logged as the
  LAST line in docker logs ('Task died: ...'); process exits 1 on failure
- log the token source (env vs netrc) and its length at startup to catch
  truncated/wrong-field netrc entries
- _run_comm_subroutine: comm crash is logged loudly but no longer relies on
  gather to surface it (bot keeps running - Discord side is independent)

communication_subroutine.py (crash found by the new stub tests):
- comm_subroutine used 'logger' before its local assignment
  (UnboundLocalError killed the whole comm layer at every startup)
- re-comment the flask_debug thread: it binds the same host:port as
  waitress, so running both dies with 'address in use'

Verified via stub-injected client: LoginFailure -> CRITICAL + exit 1,
PrivilegedIntentsRequired -> CRITICAL + exit 1, unknown exception -> full
traceback + exit 1, clean shutdown -> exit 0; comm layer no longer crashes.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

communication_subroutine.py

@@ -234,11 +234,14 @@ def comm_subroutine(stop_event: Optional[threading.Event] = None):
     :param stop_event: optional :class:`threading.Event` shared with the caller
     to coordinate a cooperative shutdown.
     """
-    logger.setLevel(logging.DEBUG)
     logger = logging.getLogger("discord")
+    logger.setLevel(logging.DEBUG)
     logger.info("Started comms")
     threads = []
-    threads.append(threading.Thread(target=flask_debug))
+    # NOTE: flask_debug is the dev server bound to the SAME host:port as
+    # waitress - running both kills the comm layer with 'address in use'.
+    # Enable it only INSTEAD of waitress_run, never alongside.
+    # threads.append(threading.Thread(target=flask_debug))
     threads.append(threading.Thread(target=waitress_run, daemon=True))
     threads.append(
         threading.Thread(