No man's land: TurnResult.unowned + release/re-claim in applyTurnResult + distinct grey map rendering (#16 P3)

- shared/protocol.ts: TurnResult.unowned (keys released this turn) + the map
  presentation contract (regionFillStyle / unownedTooltipLabel, hue-less grey)
- shared/types.ts: required GameState.unowned (cumulative mid-game releases;
  [] at init, distinct from preset-unassigned regions)
- server/engine.ts: applyTurnResult applies releases first (sole-owner only,
  never fabricating no man's land from unassigned keys), then claims against
  the post-release snapshot (gain on an ownerless key = re-claim); lone
  release is isMeaningful; prompts + user payload carry the unowned field
- server/stub.ts: unchanged behavior (never releases; e2e stays stable)
- server/db.ts: legacy rows load with unowned defaulted to []
- server/index.ts: create-game sets []; jump reference table includes
  released keys so the model can name them for re-claim
- WorldMap/App: unowned prop -> visible grey + 'No man's land' tooltip
- unit tests: 105 -> 127 (release/re-claim suites, presentation contract,
  legacy-row normalization)

server/index.ts

@@ -124,6 +124,10 @@ app.post('/api/games', (req: Request, res) => {
     events: [],
     pending: [],
     version: 1, // the first saved revision; every later mutation bumps it
+    // (v0.22, #16 P3) No man's land can only arise mid-game — a fresh game
+    // starts with nothing released; this list grows as the LLM releases
+    // regions and shrinks as they get re-claimed.
+    unowned: [],
   };
   // 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
@@ -235,7 +239,12 @@ app.post('/api/games/:id/jump', async (req, res) => {
       preset,
       state: game,
       items: game.pending,
-      regionReference: referenceForKeys(allTerritoryKeys(game)),
+      // (v0.22, #16 P3) the region reference table must also cover released
+      // (no-man's-land) keys — they belong to no nation's territory, but the
+      // model needs their names to re-claim them.
+      regionReference: referenceForKeys(
+        new Set([...allTerritoryKeys(game), ...(game.unowned ?? [])]),
+      ),
       validRegionKeys: validKeys(),
       // v0.21 (#16 P2): when the region-adjacency manifest loaded, hand the
       // engine the resolver — the turn then runs with the LLM's getNeighbours