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-host/src/gamestream/tls.rs

@@ -49,7 +49,10 @@ pub(crate) async fn serve_https(
         let (tcp, peer) = match listener.accept().await {
             Ok(v) => v,
             Err(e) => {
-                tracing::warn!(error = %e, "HTTPS accept failed");
+                // A persistent accept() error (fd exhaustion / EMFILE) would otherwise hot-spin
+                // this loop and storm the log; back off so a stuck accept can't burn a core.
+                tracing::warn!(error = %e, "HTTPS accept failed — backing off 100ms");
+                tokio::time::sleep(std::time::Duration::from_millis(100)).await;
                 continue;
             }
         };