v0.27.0 (#44): LLM-placed named map point markers

- shared: 8 MarkerTypes + MARKER_TYPE_INFO (label/color/glyph); MapMarker;
  GameState.markers (required, [] at init); TurnResult.markers {add,remove};
  MarkerSpec/MarkerInfo; FNV-1a 4-char markerId; MAX_MARKERS=400.
- data: new public/region-centroids.json (1,800 anchors = largest-part centroid
  + spread ~0.1x min-bbox) built by new idempotent scripts/build-region-centroids.mjs.
- server: regions.ts centroid loader (public/ then dist/); engine applyTurnResult
  marker ops (remove -> owner-recompute -> add, jitter, cap, never throws);
  prompt documents the contract; buildUserPrompt carries markers; stub marker-free.
- client: WorldMap symbol layer rendered as canvas per-type icons (glyph CDN dead);
  hover tooltip shows name; click focuses owning nation.
- tests: 168 -> 189 (centroids script, regions centroids, db legacy, engine markers).

server/regions.test.ts

@@ -5,8 +5,10 @@ import { tmpdir } from 'node:os';
 import path from 'node:path';
 import {
   allTerritoryKeys,
+  centroidOf,
   expandCountriesToKeys,
   hasAdjacency,
+  hasCentroids,
   hasRegionData,
   loadRegions,
   neighboursOf,
@@ -103,6 +105,7 @@ describe('regions (region-key loader, v0.19 #16 P1)', () => {
       version: 1,
       unowned: [],
       pendingNationOps: [],
+      markers: [],
     };
     // 16 GBR sub-regions + 42 FRA sub-regions, no overlap between the two.
     expect(allTerritoryKeys(state).size).toBe(58);
@@ -133,6 +136,19 @@ describe('regions (region-key loader, v0.19 #16 P1)', () => {
     expect(neighboursOf([])).toEqual([]);
   });
 
+  it('(v0.27 #44) hasCentroids() is true and centroidOf resolves a real key to a plausible location', () => {
+    expect(hasCentroids()).toBe(true);
+    const ain = centroidOf('ain-lqtt');
+    expect(ain).toBeDefined();
+    expect(ain!.lat).toBeCloseTo(46.16, 1);
+    expect(ain!.lon).toBeCloseTo(4.8, 1);
+    expect(ain!.spread).toBeGreaterThan(0);
+  });
+
+  it('(v0.27 #44) centroidOf returns undefined for an unknown key', () => {
+    expect(centroidOf('not-a-real-key-xyz')).toBeUndefined();
+  });
+
   describe('graceful degradation with no region data', () => {
     beforeEach(() => resetRegions());
 
@@ -146,6 +162,9 @@ describe('regions (region-key loader, v0.19 #16 P1)', () => {
       // and no adjacency: the LLM tool / frontier field switch off
       expect(hasAdjacency()).toBe(false);
       expect(neighboursOf(['moselle-rygy'])).toEqual([]);
+      // and no centroids: the marker-placement path degrades to a no-op
+      expect(hasCentroids()).toBe(false);
+      expect(centroidOf('ain-lqtt')).toBeUndefined();
     });
   });
 
@@ -197,6 +216,21 @@ describe('loadRegions resolves the manifest per environment (dev public/ vs prod
     expect(loadRegions(prodRoot)).toBe(true);
     expect(hasAdjacency()).toBe(false);
     expect(neighboursOf(['moselle-rygy'])).toEqual([]);
+    // and no centroids (not copied into this dist/) -> marker placement degrades
+    expect(hasCentroids()).toBe(false);
+    expect(centroidOf('ain-lqtt')).toBeUndefined();
+  });
+
+  it('(v0.27 #44) a dist/ WITH the centroids manifest loads them (prod layout)', () => {
+    copyFileSync(
+      path.join(realRoot, 'public', 'region-centroids.json'),
+      path.join(prodRoot, 'dist', 'region-centroids.json'),
+    );
+    expect(loadRegions(prodRoot)).toBe(true);
+    expect(hasCentroids()).toBe(true);
+    const ain = centroidOf('ain-lqtt');
+    expect(ain).toBeDefined();
+    expect(ain!.lat).toBeCloseTo(46.16, 1);
   });
 
   it('returns false and no data when neither public/ nor dist/ holds the files', () => {