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>

packaging/windows/build-gamepad-drivers.ps1

@@ -14,7 +14,7 @@
   --gamepad` consumes (per-driver .inf/.cat/.dll + one shared punktfunk-driver.cer).
 
   Output (-Out): pf_dualsense.{dll,inf,cat} + pf_xusb.{dll,inf,cat} + pf_mouse.{dll,inf,cat} +
-  punktfunk-driver.cer. (pf_mouse is the resident virtual HID pointer, not a gamepad — it shares
+  punktfunk-driver.cer. (pf_mouse is the resident virtual HID pointer, not a gamepad - it shares
   this pipeline + the --gamepad install path.)
 
 .EXAMPLE