feat(#46 PR 2): per-region stat lever (regionChanges) + region-stat hover

v0.29.0 — the LLM can now target individual regions' stats via
TurnResult.regionChanges (set/add per stat, clamped 0-100), applied
after nation-wide stateChanges and before the weighted-median
recompute. The map hover tooltip shows each region's own four stats.
The stub stays deterministic (regionChanges: []).

Fixes #46 (PR 2 of 2)

server/stub.ts

@@ -72,6 +72,11 @@ function truncate(s: string, n: number): string {
  * (v0.27, #44) The stub likewise NEVER places or removes a map marker (it
  * always returns `markers: { add: [], remove: [] }`) — the marker path is
  * covered by unit tests only, keeping the e2e assertions untouched.
+ *
+ * (v0.29, #46 PR 2) The stub likewise NEVER changes per-region stats (it
+ * always returns `regionChanges: []`) — the per-region lever is covered by
+ * unit tests only (see server/engine.test.ts), keeping the e2e assertions
+ * untouched.
  */
 export function deterministicTurn(p: StubPayload): TurnResult {
   const state = p.state;
@@ -133,6 +138,7 @@ export function deterministicTurn(p: StubPayload): TurnResult {
     date: addDays(state?.date ?? '1939-09-01', 2),
     events,
     stateChanges: [{ nation: pid, stat: 'military', op: 'set', value: mil }],
+    regionChanges: [], // the stub never changes per-region stats (see doc comment)
     relations: otherId ? [{ a: pid, b: otherId, set: 'ally' }] : [],
     territoryChanges,
     unowned: [], // the stub never creates no man's land (see doc comment)