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/punktfunk-core/src/client.rs

@@ -1941,7 +1941,11 @@ async fn worker_main(args: WorkerArgs) {
                                 ResyncStep::Idle => {}
                             }
                         } else {
-                            tracing::warn!("unknown control message — ignoring");
+                            tracing::warn!(
+                                tag = ?msg.first(),
+                                len = msg.len(),
+                                "unknown control message — ignoring"
+                            );
                         }
                     }
                 }

crates/punktfunk-core/src/transport/udp.rs

@@ -230,8 +230,7 @@ mod uso {
                 STATE.store(if off { 2 } else { 1 }, Ordering::Relaxed);
                 tracing::info!(
                     enabled = !off,
-                    "Windows UDP Send Offload (USO): {} (the 1 Gbps+ send lever; PUNKTFUNK_GSO=0 disables)",
-                    if off { "off" } else { "on" }
+                    "Windows UDP Send Offload (USO) resolved (the 1 Gbps+ send lever; PUNKTFUNK_GSO=0 disables)"
                 );
                 !off
             }