Record CI cache mitigation results and ignore runner logs

- Mark cache-timeout fix verified (run 1090: zero CacheService lines,
  54/54 tests, job succeeded)
- Ignore .gitea/logs/ (runner writes logs into the checkout)
- Leave collaborator's radio-easter-egg changes in the working tree
  (strings.en.json, game_manager.gd) uncommitted for review

TODO.md

@@ -10,7 +10,8 @@ checks job still passes; this is noise + risk of flaky timeouts.
 - [x] Remove the `actions/cache@v4` step from `checks` in `.gitea/workflows/build.yml`
       (Godot import takes ~4s; caching .godot is not worth the timeout risk).
 - [x] Add `GODOT_SILENCE_ROOT_WARNING=1` to godot steps to quiet container-as-root noise.
-- [ ] Push and confirm the next `.gitea/logs/` run has no `CacheService` timeouts.
+- [x] Push and confirm the next `.gitea/logs/` run has no `CacheService` timeouts (run 1090:
+      0 cache lines — previously ~12; 54/54 tests, job succeeded).
 - [x] Optional (host admin): document in `docs/RELEASING.md` that `actions/cache` needs a
       Gitea `[cache.actions]` + cache server before it can be reintroduced.