Fix mouse look swallowing by the HUD

Move guard look handling to the _input stage, recapture the cursor on
window-focus return and when clicking back into gameplay, and make HUD controls
mouse-transparent. Add regression tests for yaw/pitch and HUD mouse filters.
Verified under Xvfb with real relative mouse motion. Headless 237/237, Python
94/94, movement smoke 60 fps.

README.md

@@ -38,9 +38,9 @@ precision walk, the Joke Shop alley, the TV Studio arrival, and the prop lineup.
 > Downloads are public (no sign-in required) since the host's instance-wide
 > `REQUIRE_SIGNIN_VIEW` was disabled on 2026-10-31.
 >
-> **Latest: v0.7.2** — a cost-aware OpenRouter screenshot judge, an optional
-> Forward+ Desktop HQ build with volumetric fog/SDFGI/flashlight, distinct Joke
-> Shop and TV Studio geometry, and fitted NPC gear.
+> **Latest: v0.7.3** — mouse-look input reliability fixes, plus the v0.7.2
+> cost-aware OpenRouter judge, optional Forward+ Desktop HQ build, distinct
+> venues and fitted NPC gear.
 > Releases are built automatically when a `vX.Y.Z` tag is pushed
 > (see [`docs/RELEASING.md`](docs/RELEASING.md)); manual builds use
 > `./tools/build_releases.sh`. Installer/AppImage packaging runs in the same pipeline