fix(photon): un-shadow the U+FFFC deferred-wait handler; fix stale sidecar-deps fixture

Two independent cross-PR collisions red on main (slice 8/8):

1. fd4f756492 (salvaged from stale #54514) added an early 'drop U+FFFC
   placeholder' return at the top of _dispatch_inbound — written before
   the deferred-wait handler (6b91b50c6e/afab7ed46e) existed further
   down the same function. The early return shadowed it: _pending_fffc
   never populated, no attachment-timeout tracking, 4 tests red. Remove
   the duplicate block; the deferred handler already drops the
   placeholder AND tracks/cancels/warns.

2. 9cf2046081 tightened sidecar_deps_installed() to require
   node_modules/spectrum-ts, but test_runtime_record's _patch_spawn
   fixture still created only bare node_modules/ — 2 tests red. Mirror
   a real completed install.

tests/plugins/platforms/photon: 164/164 after; 158/164 before.

plugins/platforms/photon/adapter.py

@@ -875,19 +875,6 @@ class PhotonAdapter(BasePlatformAdapter):
             )
 
         ctype = content.get("type")
-        if ctype == "text":
-            raw_text = content.get("text") or ""
-            # iMessage emits U+FFFC OBJECT REPLACEMENT CHARACTER as a transient
-            # placeholder for some media bubbles (notably voice notes). Photon
-            # can then deliver the real attachment/voice event immediately
-            # afterwards with a different message id. If we dispatch the
-            # placeholder as a standalone text turn, the subsequent media event
-            # arrives while that turn is active and the gateway sends a bogus
-            # "Interrupting current task" busy ack. Drop placeholder-only text
-            # at the platform boundary; the real media event carries the bytes.
-            if raw_text.strip() == "\ufffc":
-                logger.debug("[photon] ignoring iMessage object-placeholder text event")
-                return
         if ctype == "reaction":
             # Route only tapbacks on messages WE sent — those are implicitly
             # addressed to the bot (feishu precedent: synthetic text event).

tests/plugins/platforms/photon/test_runtime_record.py

@@ -120,7 +120,9 @@ def _patch_spawn(
 ) -> None:
     """Stub everything _start_sidecar touches before the healthz loop."""
     sidecar_dir = tmp_path / "sidecar"
-    (sidecar_dir / "node_modules").mkdir(parents=True)
+    # sidecar_deps_installed() checks the dependency's own directory, not just
+    # node_modules/ (9cf2046081) — mirror a real completed install.
+    (sidecar_dir / "node_modules" / "spectrum-ts").mkdir(parents=True)
     monkeypatch.setattr(photon_adapter, "_SIDECAR_DIR", sidecar_dir)
     monkeypatch.setattr(photon_adapter, "_sidecar_deps_stale", lambda: False)