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.

docs/architecture.md

@@ -37,7 +37,7 @@ This document follows the structure of the arc42 architecture documentation temp
 - **MINOR** — new venues, NPC archetypes, systems, or features that are backward compatible.
 - **PATCH** — bug fixes and small polish that do not change behavior.
 
-The single source of truth for the version is `config/version` in `project.godot` (currently `0.7.2`). Each release is tagged in git as `v<version>` (e.g. `v0.6.0`). The `0.x` series is pre-1.0, so MINOR bumps may introduce breaking changes while the prototype is still stabilizing. `tools/build_releases.sh` and `tools/publish_release.sh` read the version from `project.godot`, so bumping it there is the only required step before a release. The full bump checklist lives in [`RELEASING.md`](RELEASING.md).
+The single source of truth for the version is `config/version` in `project.godot` (currently `0.7.3`). Each release is tagged in git as `v<version>` (e.g. `v0.6.0`). The `0.x` series is pre-1.0, so MINOR bumps may introduce breaking changes while the prototype is still stabilizing. `tools/build_releases.sh` and `tools/publish_release.sh` read the version from `project.godot`, so bumping it there is the only required step before a release. The full bump checklist lives in [`RELEASING.md`](RELEASING.md).
 
 ## 3. Context and Scope