Add a docs README and link checker

Add tools/check_docs.py to require READMEs only in tracked docs directories,
validate local links and verify every tracked image is linked. Gitignored
generated files such as realism runs are exempt. Document the command and add
unit tests. Python 97/97.

MEMORY.md

@@ -47,6 +47,11 @@ Session memory for durable decisions, state, and gotchas. Keep concise, remove o
 - **Radio submit fix (v0.8.1):** `RadioPanel.action_button` now connects `pressed` for normal reports; `button_down/up` remains exclusive to emergency hold-to-confirm. Regression test covers both modes.
 - **Campaign/v0.8.0:** `Campaign` owns Hollywood → Joke Shop → TV Studio progression. `campaign.json`, `shift_results.json`, `settings.json` and versioned `shift_state.json` persist separately; pause saves a checkpoint, review Continue advances, Settings resets with confirmation. Difficulty keys are `easy/normal/hard` (`ai_difficulty`); scripted QA bypasses tutorial unless `--tutorial` is passed. Help is searchable and generated from `InputBindings.REMAPPABLE`.
 - **Tutorial (0.8.0 work):** `docs/tutorial.md` is the eight-beat design; `src/game/tutorial.gd` is the pure state machine, `TutorialOverlay` is the non-blocking card, and `GameManager` wires it with a safe visitor, suppressed spawns, persisted completion/skip and Settings replay. Scripted test/capture runs bypass it unless `--tutorial` is passed; `smoke_tutorial.gd` covers completion/replay/skip.
+- **Docs validation (2026-11-02):** `python3 tools/check_docs.py` requires a README
+  only in directories containing tracked files, verifies local links and requires
+  every tracked image in a folder to be linked from its README. Gitignored
+  generated files (notably `docs/screens/realism/`) are exempt; the tool also has
+  unit tests in `tools/test_check_docs.py`.
 - **Documentation ownership (2026-11-01):** `docs/architecture.md` §12 defines the source-of-truth map and consolidation rules. Obsolete/historical plan documents are removed rather than kept; current work belongs in `TODO.md`. README/development-status/Blender AO/Forward+ stale claims were corrected. The v1.0.0 gap register and 0.8/0.9/0.9.5/1.0 roadmap live in `TODO.md`.
 - **Vision judge (v0.7.2):** `tools/openrouter_judge.py` reads `/api/v1/models`, filters image-input models with `response_format`, and ranks by advertised prompt/image/completion prices. `--model auto` (default) uses the cheapest (`z-ai/glm-5.3-flash` on 2026-11-01) with fallbacks; explicit `--model`/`GIG_LINE_JUDGE_MODEL` wins. Auth errors abort, provider/model errors fall through. Full screen judge 13/13 match, 0 diff; A/B judge ~$0.006.
 - **Desktop HQ preset (v0.7.1):** `packaging/desktop_hq/override.cfg` switches a