fix(diag): record bridge and audio interruption diagnostics (#18)

* fix(diag): record bridge events in diagnostics page

Connection lost/reconnecting/disconnected and iOS audio interruption
events now appear in the diagnostics dialog alongside existing error
snackbar entries.

* fix(diag): reduce audio callback sample verbosity to debug

The render callback diagnostic sample logged every 100 callbacks
(~2s) at INFO level, flooding the 256-entry release log buffer and
pushing out useful events. Changed to DEBUG so it only appears in
debug builds with the larger 4096-entry buffer.

* fix(diag): add timestamps to Rust diagnostic log entries

crates/chanora_audio/src/ios_voice_unit.rs

@@ -877,7 +877,7 @@ impl IosVoiceUnit {
             last_num_frames = num_frames;
             cb_count = cb_count.wrapping_add(1);
             if cb_count.is_multiple_of(100) {
-                info!(
+                debug!(
                     target: "chanora_audio",
                     cb = cb_count,
                     num_frames,