Flip ownership to region keys: shared contract + server (v0.19 P1 of #16)

The single source of truth now keys ownership by region key (one per owned
sub-region) instead of a parent-country ISO_A3:

- shared/types.ts, shared/protocol.ts: TerritoryChange / RegionMap / regionOwner
  doc flips; mapFeatureOwner now reads the feature's stamped properties.regionKey
  (never the repacked numeric feature.id, nor the sub-region id — the #6 guard).
- server/regions.ts (new, turf-free): loads region-keys.json + regions.geo.json
  once at boot; expands a nation's ISO_A3 list to its sub-regions' keys, builds
  the LLM 'regions' reference table (key -> "name (parent)"), and exposes the
  set of valid keys. Degrades gracefully when the files are missing.
- server/engine.ts: buildSystemPrompt instructs the model to use region keys;
  buildUserPrompt gains an optional regionReference table; applyTurnResult gains
  an optional validKeys set so hallucinated keys are ignored.
- server/index.ts: loads region data at boot; expands each nation's country list
  to region keys at game creation; the jump route passes the reference + valid
  keys through runTurn.

The stub is unchanged (it emits an empty, region-key-conformant territoryChanges).

server/index.ts

@@ -20,6 +20,7 @@ import { createLlmClient } from './llm';
 import { makeStubLlmClient } from './stub';
 import { askAdvisor, queueRoundItem, removeRoundItem, runTurn } from './engine';
 import { buildRegionMap } from './map';
+import { allTerritoryKeys, expandCountriesToKeys, loadRegions, referenceForKeys, validKeys } from './regions';
 import { createPresetStore } from './presets';
 import { openDb, type Db } from './db';
 
@@ -49,6 +50,9 @@ const dataDir = process.env.DATA_DIR ?? path.join(root, 'data');
 // the e2e config, so honor it as a fallback to keep all three in agreement.
 const PORT = parseInt(process.env.PORT ?? process.env.HISTORY_API_PORT ?? '4321', 10);
 const presetStore = createPresetStore(presetsDir);
+// Load the region-key manifest + geo once at boot (v0.19 #16 P1). A missing file
+// just means region expansion/reference degrade to the raw keys (server still boots).
+loadRegions(root);
 const db: Db = openDb(path.join(dataDir, 'history.db'));
 // LLM_STUB=1 → deterministic stub (tests/e2e/dev without a live model).
 const useStub = process.env.LLM_STUB === '1';
@@ -121,6 +125,10 @@ app.post('/api/games', (req: Request, res) => {
     pending: [],
     version: 1, // the first saved revision; every later mutation bumps it
   };
+  // v0.19 (#16 P1): expand each nation's ISO_A3 country list to the region keys
+  // of all its sub-regions, so ownership (and the choropleth) is at region
+  // granularity from the very first turn. Preset JSONs stay country-level.
+  for (const n of Object.values(state.nations)) n.territory = expandCountriesToKeys(n.territory);
   db.save(state);
   res.json({ game: state });
 });
@@ -227,6 +235,8 @@ app.post('/api/games/:id/jump', async (req, res) => {
       preset,
       state: game,
       items: game.pending,
+      regionReference: referenceForKeys(allTerritoryKeys(game)),
+      validRegionKeys: validKeys(),
     });
     db.save(state);
     broadcast(id, 'turn', { state, result });