fix(e2ee): use correct Element Call E2EE parameters

Inline E2EE options had 3 wrong values vs Element Call JS SDK:
- failure_tolerance=-1 (infinite, hid all DEC_FAILED) → 10
- key_ring_size=16 (too small, keys overflow) → 256
- ratchet_window_size=16 (wrong) → 10

Now uses _build_e2ee_options() which was already correct but never called.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

voice.py

@@ -261,7 +261,10 @@ def _build_e2ee_options() -> rtc.E2EEOptions:
         key_ring_size=256,
         key_derivation_function=KDF_HKDF,  # Rust FFI applies HKDF; we pass raw base keys
     )
-    return rtc.E2EEOptions(key_provider_options=key_opts)
+    return rtc.E2EEOptions(
+        encryption_type=rtc.EncryptionType.GCM,
+        key_provider_options=key_opts,
+    )
 
 
 class VoiceSession:
@@ -421,18 +424,9 @@ class VoiceSession:
             # E2EE: re-enabled after diagnostic confirmed EC encrypts audio.
             # Root cause found: set_key() only applies HKDF if the frame cryptor for that
             # participant already exists. Must call set_key() in on_track_subscribed, not at connect time.
-            key_opts = rtc.KeyProviderOptions(
-                shared_key=b"",                     # per-participant mode
-                ratchet_window_size=16,
-                ratchet_salt=b"LKFrameEncryptionKey",
-                failure_tolerance=-1,
-                key_ring_size=16,
-                key_derivation_function=KDF_HKDF,  # Rust applies HKDF matching EC JS SDK
-            )
-            e2ee_opts = rtc.E2EEOptions(
-                encryption_type=rtc.EncryptionType.GCM,
-                key_provider_options=key_opts,
-            )
+            # Parameters MUST match Element Call JS SDK: ratchetWindowSize=10, keyringSize=256,
+            # failureTolerance=10, ratchetSalt="LKFrameEncryptionKey".
+            e2ee_opts = _build_e2ee_options()
             room_opts = rtc.RoomOptions(e2ee=e2ee_opts)
             self.lk_room = rtc.Room()