fix(photon): production hardening for the gRPC-native iMessage channel (#42732)

* fix(photon): override transitive CVEs in the sidecar deps

`npm audit` flagged 7 high-severity transitive CVEs (protobufjs code injection
GHSA-66ff-xgx4-vchm + outdated @opentelemetry OTLP exporters) pulled in via
spectrum-ts -> @photon-ai/otel. npm's suggested fix downgrades spectrum-ts to a
version that targets the decommissioned spectrum host, so instead pin patched
versions via `overrides` (protobufjs 8.6.1, @opentelemetry/* 0.218.0) without
touching spectrum-ts. `npm audit` -> 0; spectrum-ts + provider still import.

* fix(photon): harden the sidecar bridge + bound the dedup cache

- constant-time sidecar control-token comparison (was `!==`, timing-attackable).
- cap the control-channel request body (2 MiB) so a compromised local peer can't
  OOM the sidecar.
- wrap the inbound gRPC stream consumer in a re-subscribe loop with capped
  exponential backoff + jitter — if the async iterator throws/ends it would
  otherwise stop inbound forever (the adapter dedupes any replay).
- add an unhandledRejection handler so a stray rejection logs instead of killing
  the process.
- dedup cache (adapter) was a true bounded LRU only for expired entries; a burst
  of unique ids within the window grew it without limit. Evict oldest at the cap.

* chore: add AUTHOR_MAP entry for PhilipAD

---------

Co-authored-by: PhilipAD <philipadsouza@gmail.com>

plugins/platforms/photon/adapter.py

@@ -414,14 +414,19 @@ class PhotonAdapter(BasePlatformAdapter):
 
     def _is_duplicate(self, msg_id: str) -> bool:
         now = time.time()
-        if len(self._seen_messages) > _DEDUP_MAX_SIZE:
-            cutoff = now - _DEDUP_WINDOW_SECONDS
-            self._seen_messages = {
-                k: v for k, v in self._seen_messages.items() if v > cutoff
-            }
-        if msg_id in self._seen_messages:
-            return True
-        self._seen_messages[msg_id] = now
+        seen = self._seen_messages
+        t = seen.get(msg_id)
+        if t is not None and now - t < _DEDUP_WINDOW_SECONDS:
+            return True  # seen, unexpired
+        # New or expired: record and enforce a HARD size bound (evict oldest,
+        # insertion-order) so a burst of unique ids within the window can't grow
+        # the dict without limit — not just the expired-only prune.
+        if msg_id in seen:
+            del seen[msg_id]  # refresh insertion order
+        seen[msg_id] = now
+        if len(seen) > _DEDUP_MAX_SIZE:
+            for old in list(seen.keys())[: len(seen) - _DEDUP_MAX_SIZE]:
+                del seen[old]
         return False
 
     async def _dispatch_inbound(self, event: Dict[str, Any]) -> None: