fix(host): native sessions on the console + GPU-aware codecs + gamestream capability

The web console Dashboard read AppState.{streaming,launch,stream}, which only the
GameStream path writes, so a native punktfunk/1 session (the DEFAULT plane) showed
"Idle / no session" while actively streaming — only the Stats page (shared recorder)
reflected it. Add a plane-neutral per-session registry (session_status.rs) the native
video loop publishes to; /status now merges both planes, reports active_sessions, and
the Stop / Request-IDR buttons reach native sessions too (so surfacing them doesn't
leave dead buttons). LocalSummary (tray) gets the same fix.

Also on the management API:
- /host codecs derive from Codec::host_wire_caps() instead of a hardcoded
  [H264,H265,AV1], so codecs the GPU can't encode no longer appear.
- ApiCodec serializes HEVC as "hevc" (matching the wire/SDP/stats label) so the same
  codec reads identically across console pages.
- HostInfo.gamestream reports whether the GameStream planes run (--gamestream), so the
  console can hide the Moonlight-only pairing UI on the native-only default host.
- StatsStatus.elapsed_ms (host-monotonic) so the capture timer doesn't mix host/browser
  clocks.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/punktfunk-host/src/main.rs

@@ -68,6 +68,7 @@ mod send_pacing;
 #[path = "windows/service.rs"]
 mod service;
 mod session_plan;
+mod session_status;
 mod session_tuning;
 mod spike;
 mod stats_recorder;