chore: update @livekit/rtc-ffi-bindings to v0.12.68

Updates FFI bindings to include:
- Add MaintainFramerateAndResolution to DegradationPreference enum (aligns with WebRTC M144)
- DISABLED is deprecated, use MAINTAIN_FRAMERATE_AND_RESOLUTION instead

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: xianshijing-lk

packages/livekit-rtc/package.json

@@ -32,7 +32,7 @@
   "dependencies": {
     "@datastructures-js/deque": "1.0.8",
     "@livekit/mutex": "^1.0.0",
-    "@livekit/rtc-ffi-bindings": "0.12.60",
+    "@livekit/rtc-ffi-bindings": "0.12.68",
     "@livekit/typed-emitter": "^3.0.0",
     "pino": "^9.0.0",
     "pino-pretty": "^13.0.0"