tools: add screenshot judge script using OpenRouter vision

- Tools/judge_screenshot.py: judges a screenshot against an expected-scene
  description via OpenRouter multimodal image understanding, reading
  OPENROUTER_API_KEY from the ignored .env. --image+--expect for one shot,
  --shots to run every review shot in Screenshots/README.md. Returns a
  {verdict, confidence, reason, missing} JSON.
- Documented in AGENTS.md (Visual review pre-check step) and Tools/README.md;
  recorded the OpenRouter payload format gotcha in MEMORY.md.

Tools/README.md

@@ -50,3 +50,4 @@ Geographic tools live in [`Geo/tools/`](../Geo/README.md) and the Blender-side b
 | Tool | Purpose |
 | --- | --- |
 | `render_screenshots.py` / `render_screenshots.sh` | Rebuilds the review map, runs the game, captures the shot list into `Screenshots/` |
+| `judge_screenshot.py` | Vision-model pre-check: judges a screenshot against an expected-scene description (`--image` + `--expect`, or `--shots` for every shot in the README). Reads `OPENROUTER_API_KEY` from `.env` (ignored). Optional helper — a human must still approve. |