feat(orchestrator): operator composer with signed text and voice

Stream -> Radio gets one line per station with state, play and stop,
autoplay and CSP refusals as row state and toast, and the speaking agent
pulsing there and in the Orbit and Chord views. The composer sends on all
seven channels; push-to-talk records with MediaRecorder, whisper.cpp
transcribes off the request thread under per-minute and per-hour caps,
and the recording travels only when "Aufnahme anhängen" is ticked.

Every operator message, the mayday clear, the day and night board
actions and a settings save that adds a stream origin take the passkey;
the hub verifies each signature once against the pinned keys before it
relays or acts. The container gets TMPDIR=/scratch so that verification
no longer fails on the read-only root.

A denial now signs its recipient: the inbox and the signing step resolve
it through one function, a claim set naming several agents leaves a
direct denial without recipient, and a recipient that changed after the
inbox showed it is refused with 409. operator_message returns only the
signed reason for a denial, never the agent's own words the radio row
quotes, and the permission hook hashes the signed recipient too.

🎯 Fix: 95 %
💥 Break: 3 %
💸 Cost: 99 %
⏱️ Time: 68 %
🛡️ Security: 100 %
🏆 Score: 100
🚦 Gate: ✅ 90/5, cost and time <= 100, security 100 %

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/hub_case.py

@@ -122,6 +122,24 @@ class HubCase(unittest.TestCase):
     def proven(self, items: list[dict], signer: Key) -> bytes:
         return json.dumps({"proof": self.signed(items, signer)}).encode()
 
+    def message_proof(self, payload: dict, signer: Key) -> dict:
+        status, _, body = self.post_json("/api/messages/sign", payload, self.guard(self.host))
+        self.assertEqual(status, 200, body)
+        return signer.proof(json.loads(body)["payload"], self.origin)
+
+    def board_proof(self, action: str, signer: Key) -> dict:
+        status, _, body = self.post_json("/api/board/sign", {"action": action}, self.guard(self.host))
+        self.assertEqual(status, 200, body)
+        return signer.proof(json.loads(body)["payload"], self.origin)
+
+    def say(self, payload: dict, signer: Key) -> tuple[int, dict, bytes]:
+        proof = self.message_proof({"upload": "", "voice": "", **payload}, signer)
+        return self.post_json("/api/messages", {"upload": "", "voice": "", **payload, "proof": proof}, self.guard(self.host))
+
+    def tell_all(self, payload: dict, signer: Key) -> tuple[int, dict, bytes]:
+        proof = self.message_proof({"to": "*", "upload": "", "voice": "", **payload}, signer)
+        return self.post_json("/api/board/broadcast", {"voice": "", **payload, "proof": proof}, self.guard(self.host))
+
     def page(self, name: str, text: str) -> str:
         path = self.pages / name
         path.write_text(text, encoding="utf-8")