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)

shared/types.ts

@@ -120,6 +120,19 @@ export interface GameState {
    * in src/App.tsx. Starts at 1 on game creation.
    */
   version: GameVersion;
+  /**
+   * (v0.22, #16 P3) Region keys that became **unowned** — "no man's land" —
+   * during play: a region that was owned and was released to no owner by a
+   * committed turn (the LLM narrates the cause in that turn's events). This is
+   * deliberately distinct from the many regions a preset never assigns, which
+   * are also unowned but were never *released* mid-game; only the keys in this
+   * list render as the distinct visible no-man's-land grey (see
+   * protocol.regionFillStyle). A region leaves the list when any nation
+   * re-claims it (an ordinary `gain`). Always `[]` on a fresh game — no
+   * man's land can only arise mid-game. Rows saved before v0.22 load with
+   * this defaulted to `[]` (see server/db.ts).
+   */
+  unowned: string[];
 }
 
 /**