chore: consolidate parallel-session WIP (HOLD — do not push)

Local snapshot of intermingled in-flight work, committed to unblock the encode
refactor (a clean ffmpeg_win.rs for the vbv-dedup follow-on). These hunks span
the same files and can't be cleanly split here; the commit bundles three
distinct workstreams that each belong in their own PR:

  - logging rework (~43 files: level re-tiering, structured fields, `?e`,
    hot-path flood latches)
  - conflicting-host detection (detect.rs + detect/{linux,windows}.rs + wiring
    in main.rs/mgmt.rs/Cargo.toml/docs/packaging)
  - standby-sink DWM-stall attribution (windows/display_events.rs + capture/
    vdisplay wiring)

NOT verified as a combination. NOT to be pushed until the refactor is done and
these are re-verified and reorganized into their proper per-workstream PRs.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

crates/pf-client-core/src/audio_wasapi.rs

@@ -60,7 +60,7 @@ impl AudioPlayer {
             .spawn(move || {
                 if let Err(e) = render_thread(pcm_rx, recycle_tx, stop_t, ready_tx, channels as u8)
                 {
-                    tracing::warn!(error = format!("{e:#}"), "audio playback thread ended");
+                    tracing::warn!(error = %format!("{e:#}"), "audio playback thread ended");
                 }
             })
             .context("spawn audio thread")?;
@@ -232,7 +232,7 @@ impl MicStreamer {
             .name("punktfunk-mic".into())
             .spawn(move || {
                 if let Err(e) = mic_thread(&connector, stop_t) {
-                    tracing::warn!(error = format!("{e:#}"), "mic uplink thread ended");
+                    tracing::warn!(error = %format!("{e:#}"), "mic uplink thread ended");
                 }
             })
             .context("spawn mic thread")?;