feat(client-linux): feature parity with the Swift client

Everything the macOS app does that stage 1 lacked, before any new
feature work (user directive):

- Input capture is now a deliberate, reversible STATE (Moonlight-
  style): engaged on stream start and click-into-video (the engaging
  click is suppressed), released by Ctrl+Alt+Shift+Q (toggles) or
  focus loss; held keys/buttons are flushed host-side on release;
  cursor hiding + shortcut inhibition follow the state; HUD hint when
  released. Per-session window handlers disconnect with the page.
- Gamepads: app-lifetime SDL service (GamepadManager parity) — pad
  list + "Forwarded controller" pin in Settings (auto = most recent),
  "Automatic" pad TYPE resolves from the physical pad at connect;
  DualSense touchpad contacts + ~250 Hz motion samples on the 0xCC
  plane (Swift GamepadWire scale constants); feedback grows adaptive-
  trigger replay and player LEDs via raw DS5 effects packets (the
  wire's 11-byte blocks drop into SDL_SendGamepadEffect verbatim);
  held pad state zeroed on pad switch/detach. sdl3 "hidapi" feature.
- Microphone uplink: PipeWire capture -> Opus 20 ms -> 0xCB datagrams
  (validated live: host received 711 mic packets), Settings toggle.
- Speed test per saved host (Swift's "Test Network Speed…"): 2 s
  probe burst, goodput/loss + recommended ~70 % bitrate, one-tap apply.
- Settings: host compositor preference (sent in the Hello), native-
  display resolution/refresh resolved from the window's monitor at
  connect (new default), bitrate ceiling to 3 Gbit/s.
- Hosts page: saved/trusted hosts section for direct pinned reconnect
  (mDNS not required), rebuilt on every page return.

Deliberately not ported: audio device pickers (PipeWire routing owns
this on Linux), resize-to-request_mode (not wired in Swift either),
pointer-lock relative mouse (stage-2 presenter, needs raw Wayland).
DualSense fidelity needs a physical pad to live-verify.

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

crates/punktfunk-host/src/encode/linux.rs

@@ -173,8 +173,8 @@ impl NvencEncoder {
             .and_then(|s| s.parse::<f32>().ok())
             .filter(|v| v.is_finite() && *v > 0.0)
             .unwrap_or(1.0);
-        let vbv_bits =
-            ((bitrate_bps as f64 / fps.max(1) as f64) * vbv_frames as f64).clamp(1.0, i32::MAX as f64);
+        let vbv_bits = ((bitrate_bps as f64 / fps.max(1) as f64) * vbv_frames as f64)
+            .clamp(1.0, i32::MAX as f64);
         unsafe {
             (*video.as_mut_ptr()).rc_buffer_size = vbv_bits as i32;
         }