feat(#52): dynamic scenario client (form → review → finalize) + e2e

Additive 'Create scenario' path (v0.31): the home screen's create-scenario
card opens a ScenarioForm (pick one of 3 light era templates + a free-text
description + an editable, era-prefilled start year) whose 'Generate world'
posts the draft request; the CheckpointReview screen shows the generated
world (per-nation stats/territory/relations + backstory) and the advisor's
checkpoint list as an approve/remove checklist, then the player picks a
nation to lead and finalizes into a saved, playable game. Both LLM steps ride
the scenario client (deterministic stub under LLM_STUB=1); a failure toasts
and stays on the current screen. The turn stub and static presets are
untouched. New e2e covers the full deterministic flow (near-future 2035,
remove checkpoint 3, lead Boreas, finalize, one empty jump) and the 3-template
manifest.

src/lib/api.ts

@@ -14,6 +14,13 @@ import type {
   RemoveQueueItemResponse,
   TurnResponse,
 } from '@shared/protocol';
+import type {
+  ScenarioCommitRequest,
+  ScenarioCommitResponse,
+  ScenarioDraftRequest,
+  ScenarioDraftResponse,
+  TemplateMeta,
+} from '@shared/scenario';
 
 async function req<T>(path: string, init?: RequestInit): Promise<T> {
   const res = await fetch(path, {
@@ -95,4 +102,24 @@ export const api = {
     req<{ regions: Record<string, { color: string; owner: string; ownerId: string }> }>(
       `/api/games/${id}/map`,
     ),
+  // --- Dynamic scenario generation (v0.31, #52) ---------------------------
+  // The additive "Create scenario" path: a two-step LLM flow (design a draft
+  // world + checkpoint list, then finalize it into a saved, playable game).
+  // The era-template manifest for the form's cards (id / name / year / blurb).
+  listScenarioTemplates: () => req<{ templates: TemplateMeta[] }>('/api/scenarios/templates'),
+  // Step 1: design a draft world + an advisor checkpoint list from an era
+  // template + a free-text description. An LLM call — can be slow; a 502
+  // means the model is down or returned nothing usable (the caller toasts).
+  draftScenario: (body: ScenarioDraftRequest) =>
+    req<ScenarioDraftResponse>('/api/scenarios/draft', {
+      method: 'POST',
+      body: JSON.stringify(body),
+    }),
+  // Step 2: finalize the approved draft (constrained to the approved
+  // checkpoints) into a new, playable game and save it. Returns the id.
+  commitScenario: (body: ScenarioCommitRequest) =>
+    req<ScenarioCommitResponse>('/api/scenarios/commit', {
+      method: 'POST',
+      body: JSON.stringify(body),
+    }),
 };