fix(MAT-258): fix DeviceStore API for Olm to-device E2EE key delivery

matrix-nio's DeviceStore has no .get() method. Use correct API:
DeviceStore[user_id].get(device_id) returns OlmDevice from inner dict.
Also fix keys_claim() to accept Dict[str, List[str]] per nio API.

This was the root cause of Element X silence — bot couldn't deliver
its E2EE key via Olm-encrypted to-device messages, so Element X
couldn't decrypt bot's audio frames.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

bot.py

@@ -3759,12 +3759,20 @@ class Bot:
 
             for user_id, device_id in targets:
                 # Get the device from the device store
-                device = olm.device_store.get(user_id, device_id) if hasattr(olm, 'device_store') else None
+                # nio DeviceStore[user_id] returns Dict[str, OlmDevice]
+                device = None
+                try:
+                    device = olm.device_store[user_id].get(device_id)
+                except KeyError:
+                    pass
                 if not device:
                     # Need to fetch device keys first
                     logger.info("Fetching device keys for %s/%s", user_id, device_id)
                     await self.client.keys_query()
-                    device = olm.device_store.get(user_id, device_id) if hasattr(olm, 'device_store') else None
+                    try:
+                        device = olm.device_store[user_id].get(device_id)
+                    except KeyError:
+                        pass
 
                 if not device:
                     logger.warning("Device %s/%s not found in store, sending unencrypted", user_id, device_id)
@@ -3776,7 +3784,7 @@ class Bot:
                 if not session:
                     # Claim one-time key and create session
                     logger.info("Claiming one-time key for %s/%s", user_id, device_id)
-                    claim_resp = await self.client.keys_claim(user_id, device_id)
+                    await self.client.keys_claim({user_id: [device_id]})
                     session = olm.session_store.get(device.curve25519)
 
                 if session: