feat(rust): the live map draws monuments by label, minor labels hidden (PLAN_REDESIGNS §4, D196)

A switch per monument label, a fleet default and a per-server override, on
Admin -> Rust visibility's live map card. Substations, caves, train tunnels,
wells and the other minor labels start hidden; every other label is drawn,
so a monument a game update adds appears. GET /map leaves hidden labels out
of the answer, so the website and the app both lose them.

No schema change: rows are map.marker.<label key> in rust_settings and
rust_map_overrides. No wire change.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E14m6SuuY6i1vASFeGDBeY

client/test/mapMarkers.test.js

@@ -0,0 +1,65 @@
+// ── Which monument labels a map draws (PLAN_REDESIGNS §4, D196) ───────────
+//
+// The admin card must agree with the server about what a switch means, or the
+// page says a label is drawn while the map leaves it out. These are the ways it
+// could disagree: case, the built-in list, the fleet under a server, and a
+// switch set back to its default.
+
+import test from 'node:test'
+import assert from 'node:assert/strict'
+
+import { builtIn, fleetLabels, fleetShows, markerDiff, markerKey, serverShows, setFleet, setServer } from '../src/lib/mapMarkers.js'
+
+const MINOR = ['Substation', 'Jungle Swamp', 'Ranch']
+
+test('a label becomes the same key the server stores', () => {
+  assert.equal(markerKey('  jungle   Swamp '), 'jungle swamp')
+  assert.equal(markerKey(null), '')
+})
+
+test('the minor labels start hidden and every other label drawn', () => {
+  assert.equal(builtIn(MINOR, 'substation'), false)
+  assert.equal(builtIn(MINOR, 'something facepunch added'), true)
+})
+
+test('a server switch wins over the fleet, and the fleet over the built-in list', () => {
+  assert.equal(fleetShows(MINOR, {}, 'substation'), false)
+  assert.equal(fleetShows(MINOR, { substation: true }, 'substation'), true)
+  assert.equal(serverShows(MINOR, { substation: true }, {}, 'substation'), true)
+  assert.equal(serverShows(MINOR, { substation: true }, { substation: false }, 'substation'), false)
+  assert.equal(serverShows(MINOR, {}, { 'power plant': false }, 'power plant'), false)
+})
+
+test('the fleet list is every server’s labels and the minor list, each once', () => {
+  const labels = fleetLabels(MINOR, [
+    { markerLabels: [{ key: 'substation', label: 'Substation', count: 31 }, { key: 'harbor', label: 'Harbor', count: 2 }] },
+    { markerLabels: [{ key: 'substation', label: 'Substation', count: 12 }] },
+    {},
+  ])
+  assert.deepEqual(
+    labels.map((l) => [l.key, l.count]),
+    [
+      ['harbor', 2],
+      ['jungle swamp', 0],
+      ['ranch', 0],
+      ['substation', 43],
+    ],
+  )
+})
+
+test('setting the fleet back to the built-in answer clears the row instead of copying it', () => {
+  assert.deepEqual(setFleet(MINOR, {}, 'substation', true), { substation: true })
+  assert.deepEqual(setFleet(MINOR, { substation: true }, 'substation', false), {})
+  assert.deepEqual(setFleet(MINOR, {}, 'harbor', false), { harbor: false })
+})
+
+test('a server set to follow the fleet loses its own switch', () => {
+  assert.deepEqual(setServer({ substation: true }, 'substation', null), {})
+  assert.deepEqual(setServer({}, 'substation', false), { substation: false })
+})
+
+test('the diff sends a changed switch as its value and a removed one as null', () => {
+  assert.equal(markerDiff({ a: true }, { a: true }), null)
+  assert.deepEqual(markerDiff({ a: true, b: false }, { a: false, c: true }), { a: false, b: null, c: true })
+  assert.equal(markerDiff(undefined, {}), null)
+})