fix: enable Rust tracing → Android logcat via tracing-android

Rust tracing subscriber was never initialized — all info!/warn!/error!
calls in the engine went to /dev/null. This meant our send/recv health
logging was invisible and we couldn't confirm the congestion fix was
active.

Now initializes tracing-android layer on first nativeInit(), routing
all Rust logs to logcat under tag "wzp_android". Also expanded logcat
filter in DebugReporter to capture engine-level log lines.

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

android/app/src/main/java/com/wzp/debug/DebugReporter.kt

@@ -138,7 +138,16 @@ class DebugReporter(private val context: Context) {
                     line.contains("AudioFlinger") ||
                     line.contains("DebugReporter") ||
                     line.contains("QUIC") ||
-                    line.contains("quinn")
+                    line.contains("quinn") ||
+                    line.contains("send task") ||
+                    line.contains("recv task") ||
+                    line.contains("send stats") ||
+                    line.contains("recv stats") ||
+                    line.contains("send_media") ||
+                    line.contains("FEC block") ||
+                    line.contains("recv gap") ||
+                    line.contains("frames_dropped") ||
+                    line.contains("opus")
                 }
                 .joinToString("\n")
         } catch (e: Exception) {