Disable unreliable Gitea Godot cache steps

Gitea cache restores were inconsistent and cache saves timed out or were
rejected as reserved by another job. Remove the cache steps and keep direct
4.7.2 downloads; document the evaluation and when to retry. The workflow is
otherwise clean (no .github/ci.yml exists).

docs/architecture.md

@@ -188,7 +188,7 @@ Future options include external analytics, cloud saves, or replay sharing, but t
 
 A continuous-integration pipeline keeps the headless test suite green on every change and publishes tagged releases.
 
-- **Workflow:** `.gitea/workflows/build.yml` runs on pushes, pull requests, tags, and manual dispatches. The `checks` job restores/caches Godot 4.7.2, imports the project, and runs `res://src/test/test_runner.gd`; it fails on a non-zero exit code or any `SCRIPT ERROR` in the output.
+- **Workflow:** `.gitea/workflows/build.yml` runs on pushes, pull requests, tags, and manual dispatches. The `checks` job installs Godot 4.7.2, imports the project, and runs `res://src/test/test_runner.gd`; it fails on a non-zero exit code or any `SCRIPT ERROR` in the output.
 - **Build job:** runs for tags and manual dispatches. It installs export templates, exports Linux/Windows/macOS and the non-threaded Web build, packages the NSIS installer, Linux AppImage and optional Desktop HQ zip, verifies the installer contents, and uploads the artifacts.
 - **Publish job:** tag builds call `tools/publish_release.sh` to create the Gitea release and upload the standard artifacts plus the optional Desktop HQ zip. The script uses `GITEA_TOKEN` when configured and otherwise reuses the runner's checkout extraheader credentials.
 - **Hosting:** the repository lives on Gitea (`https://git.allucanget.biz/zwitschi/security-game`). Export templates must match the pinned Godot version; macOS builds are unsigned and need quarantine guidance or notarization for wider distribution.