style: apply rustfmt to establish clean baseline before refactor

Pre-refactor baseline state:
- 79 lib tests + 3 integration tests pass (1 integration test #[ignore])
- cargo clippy --all-targets -- -D warnings clean
- cargo build --release clean

No semantic changes; only rustfmt drift correction across 6 files.

src/stats.rs

@@ -201,7 +201,8 @@ impl PipelineStats {
     /// Update duplicate frames skipped counter (absolute value from atomic).
     /// Computes delta from previous value, like set_pipewire_dropped.
     pub fn set_duplicate_frames_skipped(&mut self, total_skipped: u64) {
-        self.duplicate_frames_skipped = total_skipped.saturating_sub(self.prev_duplicate_frames_skipped);
+        self.duplicate_frames_skipped =
+            total_skipped.saturating_sub(self.prev_duplicate_frames_skipped);
         self.prev_duplicate_frames_skipped = total_skipped;
     }
 
@@ -356,7 +357,7 @@ impl std::fmt::Display for StatsSnapshot {
         // central tendency and tail behaviour in the same glance.
         write!(
             f,
-             "elapsed={:.1}s capture_fps={:.1} encoded_fps={:.1} sent_fps={:.1} \
+            "elapsed={:.1}s capture_fps={:.1} encoded_fps={:.1} sent_fps={:.1} \
               capture_frames={} encoded_frames={} sent_frames={} \
               pw_dropped={} duplicate_frames_skipped={} \
               cap_q={} enc_q={} \