Add adaptive jitter buffer, BWE, and mid-session codec renegotiation.

Receiver pipeline gets configurable jitter buffering with live stats in the debug overlay; sender/receiver share AdaptiveNetworkControlPlane for congestion-aware bitrate and codec switches without a protocol version bump.

Co-authored-by: Cursor <cursoragent@cursor.com>

ndk/jni/libvpx_bridge.c

@@ -35,6 +35,7 @@
 typedef struct {
     unsigned long magic;
     vpx_codec_ctx_t codec;
+    vpx_codec_enc_cfg_t cfg;
     vpx_image_t img;
     int width;
     int height;
@@ -209,6 +210,7 @@ Java_com_foxx_androidcast_media_codec_jni_NativeCodecBridge_nativeVpxEncoderCrea
         (*env)->ReleaseStringUTFChars(env, mime, mime_utf);
         return 0L;
     }
+    ctx->cfg = cfg;
     /* VP8 and VP9 both use VP8E_SET_CPUUSED (see libvpx tests / vp9_cx_iface.c). */
     vpx_codec_control(&ctx->codec, VP8E_SET_CPUUSED, 8);
 
@@ -338,6 +340,28 @@ Java_com_foxx_androidcast_media_codec_jni_NativeCodecBridge_nativeVpxRequestKeyf
 #endif
 }
 
+JNIEXPORT jboolean JNICALL
+Java_com_foxx_androidcast_media_codec_jni_NativeCodecBridge_nativeVpxSetBitrate(
+        JNIEnv *env, jclass clazz, jlong handle, jint bitrateKbps) {
+    (void) env;
+    (void) clazz;
+#if !ANDROIDCAST_HAVE_LIBVPX
+    (void) handle;
+    (void) bitrateKbps;
+    return JNI_FALSE;
+#else
+    VpxEncoderCtx *ctx = enc_from_handle(handle);
+    if (ctx == NULL || bitrateKbps <= 0) {
+        return JNI_FALSE;
+    }
+    ctx->cfg.rc_target_bitrate = bitrateKbps;
+    if (vpx_codec_enc_config_set(&ctx->codec, &ctx->cfg) != VPX_CODEC_OK) {
+        return JNI_FALSE;
+    }
+    return JNI_TRUE;
+#endif
+}
+
 JNIEXPORT jlong JNICALL
 Java_com_foxx_androidcast_media_codec_jni_NativeCodecBridge_nativeVpxDecoderCreate(
         JNIEnv *env, jclass clazz, jstring mime) {