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>

Documentation/data-and-images.md

@@ -326,6 +326,8 @@ Wing layout lives in `client/src/utils/movementHallLayout.ts` (up to 55 works pe
 
 **Paintings must not sit in front of mid-wall bay columns/pilasters.** Column Z centres use the same `bayPositions` formula as the period modules. Keep-out half-widths per `details` kind live in `client/src/utils/sideColumnKeepOuts.ts` (`SIDE_WALL_COLUMN_RHYTHMS`: gothic, roman, quattrocento, cinquecento, mannerist, neoclassical, gothic-revival, art-nouveau). Side-wall hang packs into the gaps between those keep-outs and **grows hall depth** when needed; columns are never moved. Windows also treat column keep-outs as occupied so they do not land on shafts. Regression: `server/__tests__/painting-column-clearance.test.js`.
 
+Run `npm test` after touching any interior module, hall layout or tint: the rules above are covered by 15 suites under `server/__tests__/` that parse these source files directly — see [FAC.md](FAC.md) § Tests.
+
 The same U-hang applies to artist halls and guided tours (artist halls have no period bay columns). Hall lighting is **shared** (no per-painting spotlights) so `MeshStandardMaterial` walls stay within WebGL light limits — see [basics.md](basics.md) § Shared 3D behaviour. To change a movement’s look, edit its entry in `movement-interior-styles.ts` and rebuild the client.
 
 ## Historical event markers (frontend timeline)