Merge perf/first-frame-latency: driver proto v4 + first-frame/resize latency (P0-P2)

Brings the first-frame-latency branch (P0.1 transition tracing, P1.1/P1.2
Welcome-time display prep, P2 in-place resize; pf-driver-proto v3 -> v4 with
IOCTL_UPDATE_MODES) onto current main. The branch predates the W6.2/W7 splits,
so git's rename detection carried most of it into the moved crates
(pf-capture idd_push, pf-vdisplay manager/pf_vdisplay, pf-win-display,
pf-driver-proto, the driver workspace) and the punktfunk1.rs remainder was
re-homed by hand:

- native/handshake.rs: welcome/start trace marks + the Welcome-time display
  prep spawn (the prep thread BECOMES the stream thread; hand-off via a
  SyncSender<SessionContext>). negotiate() gains bringup/quit/stop and returns
  the PrepHandle.
- native.rs: bringup/resize_ms creation + the stop/quit flags hoisted BEFORE
  the handshake (the close watcher splits: flags pre-handshake, lifecycle
  events post-handshake where `hello` exists); punch_done stamp; the data
  plane adopts the prep thread's result or builds inline.
- native/stream.rs: SessionContext/SendStats carry the trace; send_loop
  finishes it on the first video packet; the resize path gains the in-place
  fast path (try_inplace_resize) with the full rebuild as fallback, restructured
  so both share the post-rebuild bookkeeping; prepare_display/PreparedDisplay/
  PrepHandle; build_pipeline(+retry) thread the stage marks.
- session_status/mgmt: ttff_ms + last_resize_ms per session (union with the
  lifecycle-events fields main added to the same spots).
- pf-capture: Capturer gains capture_target_id() + resize_output() defaults.
- pf-vdisplay manager: perf's faster activation poll (60x50ms) + the settle
  floor before the PnP sweep, on main's knobs/no-trait shape.

Also: packaging/windows/build-gamepad-drivers.ps1 is ASCII again (an em-dash
from the pf-mouse work tripped windows-host.yml's locale-safety gate on main).

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

crates/punktfunk-host/src/session_status.rs

@@ -40,6 +40,11 @@ struct LiveSession {
     client: String,
     /// Whether the session negotiated HDR — carried on the lifecycle events.
     hdr: bool,
+    /// Completed bring-up total (hello → first packet), ms; 0 until the first packet left. Written
+    /// once by the session's [`crate::bringup::Trace`] (latency plan P0.1).
+    ttff_ms: Arc<AtomicU32>,
+    /// Most recent completed mid-stream resize (reconfigure → pipeline rebuilt), ms; 0 = none yet.
+    last_resize_ms: Arc<AtomicU32>,
 }
 
 /// A resolved read of one live session, for the `/status` view.
@@ -50,6 +55,10 @@ pub struct SessionSnapshot {
     pub fps: u32,
     pub bitrate_kbps: u32,
     pub codec: Codec,
+    /// Bring-up total (hello → first packet), ms; 0 while still bringing up (latency plan P0.1).
+    pub time_to_first_frame_ms: u32,
+    /// Most recent mid-stream resize total, ms; 0 = no resize this session.
+    pub last_resize_ms: u32,
 }
 
 fn registry() -> &'static Mutex<Vec<LiveSession>> {
@@ -84,6 +93,8 @@ pub fn register(
     force_idr: Arc<AtomicBool>,
     client: String,
     hdr: bool,
+    ttff_ms: Arc<AtomicU32>,
+    last_resize_ms: Arc<AtomicU32>,
 ) -> LiveSessionGuard {
     let id = next_id();
     let session = LiveSession {
@@ -95,6 +106,8 @@ pub fn register(
         force_idr,
         client,
         hdr,
+        ttff_ms,
+        last_resize_ms,
     };
     crate::events::emit(crate::events::EventKind::SessionStarted {
         session: session_ref(&session),
@@ -140,6 +153,8 @@ pub fn snapshot() -> Vec<SessionSnapshot> {
                 fps,
                 bitrate_kbps: s.bitrate_kbps.load(Ordering::Relaxed),
                 codec: s.codec,
+                time_to_first_frame_ms: s.ttff_ms.load(Ordering::Relaxed),
+                last_resize_ms: s.last_resize_ms.load(Ordering::Relaxed),
             }
         })
         .collect()