Initial scaffold: Nakama backend, Godot client, content schema

Sets up the Step 1 (Project Foundation) and Step 2 (Content Schemas) scaffold
from the implementation sequence. Includes Docker Compose stack, Nakama
TypeScript module stubs, PostgreSQL migration, Godot 4 project shell with
scene stubs and NakamaClient singleton, YAML content schemas for all entity
types, and example data for 3 characters, 2 jobs, and all 7 core resources.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

nakama/modules/gacha.ts

@@ -0,0 +1,112 @@
+// gacha.ts — authoritative pull execution
+//
+// All pull outcomes are resolved server-side. The client sends a banner ID and
+// pull count; this module resolves rarity, determines the result from the
+// banner pool, updates pity counters, deducts currency, and records pull
+// history. Nothing here is computed client-side.
+//
+// Pity model (PoC defaults — all values should be content-driven):
+//   - Soft pity begins at 70 pulls (increasing rate toward hard pity)
+//   - Hard pity at 90 pulls guarantees SSR
+//   - Featured SSR rate-up: 50% chance when SSR hits
+//   - Pity carries over between sessions but NOT between different banners
+//     unless the banner explicitly declares carry-over.
+
+export interface BannerDefinition {
+  id: string;
+  name: string;
+  type: "standard" | "featured" | "event";
+  pull_cost_currency: string;
+  pull_cost_amount: number;
+  multi_cost_amount: number; // cost for 10-pull; usually 10x single minus one
+  pool: BannerPoolEntry[];
+  soft_pity_start: number;
+  hard_pity: number;
+  featured_character_ids: string[];
+  active_from: number; // unix ms
+  active_until: number | null; // null = permanent
+}
+
+export interface BannerPoolEntry {
+  character_id: string;
+  rarity: "R" | "SR" | "SSR" | "UR";
+  base_weight: number;
+}
+
+export interface PullRecord {
+  banner_id: string;
+  character_id: string;
+  rarity: string;
+  pulled_at: number;
+  pity_count_at_pull: number;
+  was_soft_pity: boolean;
+  was_hard_pity: boolean;
+}
+
+// ── RPCs ──────────────────────────────────────────────────────────────────
+
+export function rpcGachaPull(
+  ctx: nkruntime.Context,
+  logger: nkruntime.Logger,
+  nk: nkruntime.Nakama,
+  payload: string
+): string {
+  // TODO PR 5: implement full pull resolution
+  // Stub returns a placeholder response so the endpoint is registered and
+  // callable from the Godot client in PoC step 1.
+  logger.info(`gacha/pull stub called by ${ctx.userId}`);
+
+  const req = JSON.parse(payload || "{}");
+  const bannerId: string = req.banner_id ?? "standard";
+  const count: number = req.count ?? 1;
+
+  if (count !== 1 && count !== 10) {
+    throw new Error("Pull count must be 1 or 10");
+  }
+
+  return JSON.stringify({
+    ok: false,
+    error: "not_implemented",
+    message: "Gacha pull system is stubbed. Implement in PR 5.",
+    banner_id: bannerId,
+    count,
+  });
+}
+
+export function rpcListBanners(
+  ctx: nkruntime.Context,
+  logger: nkruntime.Logger,
+  nk: nkruntime.Nakama,
+  _payload: string
+): string {
+  // TODO PR 5: load active banners from content storage
+  logger.info(`gacha/banners stub called by ${ctx.userId}`);
+  return JSON.stringify({ banners: [], message: "Banner list is stubbed. Implement in PR 5." });
+}
+
+export function rpcGetPity(
+  ctx: nkruntime.Context,
+  logger: nkruntime.Logger,
+  nk: nkruntime.Nakama,
+  payload: string
+): string {
+  // TODO PR 5: read pity counters from player storage
+  const req = JSON.parse(payload || "{}");
+  return JSON.stringify({
+    banner_id: req.banner_id ?? "standard",
+    current_pity: 0,
+    soft_pity_start: 70,
+    hard_pity: 90,
+    message: "Pity counter is stubbed. Implement in PR 5.",
+  });
+}
+
+export function rpcGetPullHistory(
+  ctx: nkruntime.Context,
+  logger: nkruntime.Logger,
+  nk: nkruntime.Nakama,
+  _payload: string
+): string {
+  // TODO PR 5: load pull history from player storage
+  return JSON.stringify({ history: [], message: "Pull history is stubbed. Implement in PR 5." });
+}