Document the test suite in the command and setup docs.

`package.json` has had a `test` script since the interior-polish work landed,
and 12 files under `server/__tests__/` now guard hall geometry, clearance,
brightness, window styles and the movement-links validators. Nothing outside
`data-and-images.md` said the suite existed, and no document said how to run
it — despite Bible.md requiring tests to be written before the code.

FAC.md gains a Tests section between Verify and Build frontend: the command,
what the suite covers by area, and the two properties that make it cheap to
run — no test framework (Node's built-in runner) and no database or server,
since the tests read the client's style and geometry modules from disk.

setup.md lists `npm test` first in the Run table and notes on the Node
prerequisite that the script depends on `node --test` expanding `**` itself.
README.md gets the command beside the dev-server ones, and the interiors
section of data-and-images.md now points at the suite that enforces its rules.

Docs only; no source changes. Verified by running the suite (15 suites, 41
tests, all passing) and by confirming from PowerShell — which does not expand
globs — that the runner does its own pattern matching.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

README.md

@@ -86,6 +86,14 @@ Operator guide: [Documentation/environments.md](Documentation/environments.md).
 npm run dev:web   # Vite :5173, API :3451
 ```
 
+**Tests** (Node’s built-in runner — no database or server needed):
+
+```bash
+npm test   # 15 suites, 41 tests
+```
+
+Per [Documentation/Bible.md](Documentation/Bible.md), write the test before the code it covers.
+
 **Local HMR:**
 
 ```bash