feat(#50): make the four 0-100 stats consequential

- Add a hard military conquest gate (canConquer, CONQUEST_MILITARY_MARGIN=15)
  enforced in applyTurnResult: a contested invasion is repelled when the
  attacker's military is more than 15 below the defender's; re-claims of
  unowned regions are never gated. Emits a new 'repelled' event.
- Document the soft levers in the system prompt: stability<30 + gathering
  marker -> non-military takeover; economy growth/decay drives other stats.
- Emit bounded frontierMilitary (per-neighbour balance) and takeoverRisks
  hints in the user payload (only when present).
- repelled outcome color (#9f1239); full unit test coverage; stub untouched.
- Bump to v0.30.0.

Fixes #50

shared/types.ts

@@ -79,7 +79,15 @@ export const EVENT_TYPES: EventType[] = [
   'cultural',
 ];
 
-export type EventOutcome = 'success' | 'failure' | 'partial' | 'neutral';
+/**
+ * The outcome of a narrative event. `success` / `failure` / `partial` /
+ * `neutral` are the four the LLM is asked to emit. `repelled` (v0.30, #50) is
+ * reserved for the engine: it is emitted automatically when the military hard
+ * gate rejects a contested conquest (an invasion whose attacker was more than
+ * `CONQUEST_MILITARY_MARGIN` below the defender) — the LLM never produces it,
+ * and the client renders it in a distinct muted-red failure tone.
+ */
+export type EventOutcome = 'success' | 'failure' | 'partial' | 'neutral' | 'repelled';
 
 // --- Map markers (v0.27, #44) -------------------------------------------------
 //