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

CHANGELOG.md

@@ -2,6 +2,20 @@
 
 All notable changes to **History** are listed here, newest first.
 
+## v0.30.0 — 2026-10-15 08:22
+- **#50: make the four 0–100 stats consequential — a hard military conquest gate, soft stability takeovers, and economy growth/decay.** The four stats now actually drive outcomes instead of being decorative. **Military is a hard gate:** a contested invasion (a region's sole owner changing hands) is repelled whenever the attacker's military is **more than `CONQUEST_MILITARY_MARGIN = 15`** below the defender's — equal or within 15 still wins. The engine enforces this in `applyTurnResult` and emits a new `repelled` event when it fires; **re-claims of unowned (no man's land) regions are not gated** (there is no defender). **Stability is a soft lever:** the system prompt documents that a nation whose stability is below 30 *and* that hosts a `gathering` marker can suffer a **non-military takeover** (coup / revolution / faction seizure) — narrated by the LLM with a political/social success event, a gathering marker, and a downward stability/economy shock. **Economy is a soft lever:** a strong (rising) economy trends the other stats up (growth) and a collapsing economy drags them down (decay), reflected via `stateChanges` / `regionChanges`. A **frontier military-balance hint** and a **takeover-risks** hint are emitted in the user payload (each only when present) so the model — and the player, via the same data — sees the levers before acting. The stub stays 100% deterministic and untouched; e2e is unaffected (the UK/wwii-1939 e2e has an empty frontier, so the gate is vacuous there).
+  - **Protocol (`shared/protocol.ts`).** New `CONQUEST_MILITARY_MARGIN = 15` and a pure `canConquer(attackerMil, defenderMil, margin = CONQUEST_MILITARY_MARGIN)` — `!(attackerMil < defenderMil - margin)` (proceeds unless the attacker is strictly more than the margin below the defender).
+  - **Types (`shared/types.ts`).** `EventOutcome` gains `'repelled'` (engine-only; the LLM never produces it).
+  - **Colors (`src/lib/colors.ts`).** `OUTCOME_COLORS.repelled = '#9f1239'` — a muted rose-800, distinct from `failure` (`#ef4444`) and `neutral` (`#94a3b8`).
+  - **Engine (`server/engine.ts`).**
+    - `applyTurnResult` gains an optional `regionNameOf` (5th optional param, after `geoOf`) and the **military hard gate** inside the snapshot-first claims loop: for each contested key (a gainer's `gain` whose current sole owner is a *different* nation), it compares the gainer's start-of-turn military to the owner's via `canConquer`; on a fail it keeps the key with the owner, leaves both nations' military untouched, and pushes one `repelled` military event (`"<Attacker>'s invasion of <region name> was repelled by <Defender>."`, using the region's geo display name when known). Re-claims (`owner === undefined`) bypass the gate.
+    - `buildSystemPrompt` gains a **"HOW THE FOUR 0–100 STATS DRIVE OUTCOMES"** section: the enforced military gate (incl. the no-man's-land carve-out), the soft stability takeover, and the economy growth/decay lever — present in both tool and plain modes.
+    - `buildUserPrompt` computes and emits two new, bounded payload fields (each only when non-empty, the rest of the payload untouched): `frontierMilitary` (one line per frontier neighbour: `[Your military: X] vs [Name: Y] — a direct invasion could succeed | would be repelled`, decided by `canConquer`) and `takeoverRisks` (one line per nation with stability < 30 *and* a `gathering` marker: `Name (stability N, a gathering is in progress)`).
+    - `runTurn` threads `regionNameOf` through to `applyTurnResult`.
+  - **Server route (`server/index.ts`).** The `/jump` route wires `regionNameOf: (k) => regionName(k)` so repelled invasions name the region properly.
+  - **Stub (`server/stub.ts`).** Unchanged (100%) — it never releases, never proposes a nation op, and its one-conquest behavior is what e2e relies on; the new gate / takeover / economy paths are covered by unit tests only.
+  - **Unit tests.** `server/protocol.test.ts`: `canConquer` edges (equal, within margin, over margin, gap == margin, gap == margin + 1, margin = 0). `server/engine.test.ts`: the hard gate (proceed within margin / proceed when stronger / **repel when over margin** with a correct `repelled` event + region display name + attacker untouched / **re-claim ungated** / boundary at exactly the margin and one past it); the system prompt documents all three mechanics in both modes; the user prompt emits `frontierMilitary` (could-succeed vs repelled per neighbour) and `takeoverRisks` (and omits both fields when no frontier / no markers).
+
 ## v0.29.0 — 2026-10-15 01:05
 - **#46 (PR 2 of 2): per-region stat lever — the LLM can now target individual regions' stats, and the map hover shows them.** The LLM gains a fine-grained `TurnResult.regionChanges` field (alongside the existing nation-wide `stateChanges`): each entry targets **one** region's own stats by its region key (preferred) or case-insensitive name. A `set` replaces the value; an `add` increments it (both clamped 0–100 at apply time). Region-level changes are applied **after** nation-wide `stateChanges` (so they override the nation-level value for that one region) and **before** the weighted-median recompute, which propagates every region's final value into its owning nation's derived `stats`. A region with no stats entry (unowned / no man's land) is a no-op. The map hover tooltip now shows each region's own four stats (military / economy / stability / population) alongside the region name and owner chip; the `NationPanel` keeps showing the nation-level derived aggregate. The stub stays fully deterministic (`regionChanges: []`) — e2e assertions are untouched.
   - **Protocol (`shared/protocol.ts`).** New `RegionStatChange = { region: string; stat: StatKey; op: 'set'|'add'; value: number }`. `TurnResult.regionChanges: RegionStatChange[]` is **required** (default `[]`); sits right after `stateChanges`.