fix(gateway): gate oversized Telegram voice/audio before download (#44245)

* fix(gateway): gate oversized Telegram voice/audio before download

Adds a pre-download size check to the Telegram voice and audio inbound
paths. Files that exceed _max_doc_bytes (default 20 MB) are rejected
before get_file() is called, preventing silent OOM-style stalls on large
uploads. A human-readable note is appended to the event text so the
model can explain the limit to the user.

Also extends 403 entitlement detection in recover_with_credential_pool
to cover two additional cases: 'oauth authentication is currently not
allowed for this organization' and Anthropic anthropic_messages-mode 403s,
both of which should be treated as entitlement failures rather than
transient errors.

Tests: 7 new cases in test_telegram_voice_v0_regressions.py covering
the size gate (accept, reject, note text) and the STT-failure notice path.

Salvaged from #40487 (cryptopafi) — cherry-picked the Telegram voice
policy and 403 entitlement fixes; LiveKit/Discord/uv.lock workstreams
left for separate PRs.

* test(gateway): drop orphaned voice tests not backed by this PR

The cherry-picked test file from #40487 included 3 tests for STT-failure
notice and voice-mode (_handle_voice_command 'on' -> voice_only) behavior
that this PR intentionally does NOT salvage (those belong to the LiveKit/
voice-policy workstreams left in #40487). They fail on both this branch
and clean main because the feature code isn't present.

Keep only the 2 tests backed by code actually in this PR:
- test_telegram_audio_size_gate_rejects_oversized_media_before_download
  (covers the _telegram_media_size_allowed guard this PR adds)
- test_voice_tts_is_explicit_audio_reply_opt_in (matches current main)

Removed now-unused imports (MessageEvent, MessageType, AsyncMock).

agent/agent_runtime_helpers.py

@@ -679,15 +679,28 @@ def recover_with_credential_pool(
         # long-running TUI sessions stuck on stale tokens until the user
         # exited and reopened.
         is_entitlement = agent._is_entitlement_failure(error_context, status_code)
+        _auth_haystack = " ".join(
+            str(error_context.get(k) or "").lower()
+            for k in ("message", "reason", "code", "error")
+            if isinstance(error_context, dict)
+        )
+        if (
+            not is_entitlement
+            and status_code == 403
+            and "oauth authentication is currently not allowed for this organization" in _auth_haystack
+        ):
+            is_entitlement = True
+        if (
+            not is_entitlement
+            and status_code == 403
+            and (agent.provider or "") == "anthropic"
+            and getattr(agent, "api_mode", "") == "anthropic_messages"
+        ):
+            is_entitlement = True
         if not is_entitlement and status_code == 403 and (agent.provider or "") == "xai-oauth":
-            _disambiguator_haystack = " ".join(
-                str(error_context.get(k) or "").lower()
-                for k in ("message", "reason", "code", "error")
-                if isinstance(error_context, dict)
-            )
             _is_xai_auth_failure = (
-                "[wke=unauthenticated:" in _disambiguator_haystack
-                or "oauth2 access token could not be validated" in _disambiguator_haystack
+                "[wke=unauthenticated:" in _auth_haystack
+                or "oauth2 access token could not be validated" in _auth_haystack
             )
             if not _is_xai_auth_failure:
                 is_entitlement = True