Implement CHUNK #2: server layer, core schemas/adapters, contract tests, seed

Complete the server-backed storage layer for PubScript so the app can run
against a real Fastify + SQLite backend instead of only local IndexedDB.

Server (@pubscript/server):
- db.ts: better-sqlite3 schema + migrations (users, shares, projects, books,
  chapters, entities, boards, ai_sessions, audit); WAL mode; idempotent
  admin bootstrap via PUBSCRIPT_ADMIN_EMAIL/PASSWORD.
- auth.ts: argon2 hashing, JWT-ish session tokens, guards, auth routes.
- routes.ts: REST CRUD for projects/books/chapters/entities/boards/ai_sessions
  with multi-tenant isolation and optimistic concurrency (baseRev).
- ws.ts: Fastify websocket hub for autosave + presence events.
- mapping.ts: row <-> core type conversion.

Core (@pubscript/core):
- Zod domain schemas (projects, books, chapters, entities, boards, ai_sessions)
  exported from index.
- storage-local.ts (IndexedDB/Dexie) and storage-server.ts (REST) adapters
  implementing the StorageAdapter contract.

Tests & tooling:
- storage.contract.test.ts: parameterized over both adapters; wired as
  `pnpm contract` and added to CI.
- seed.ts (`pnpm --filter server seed`): creates demo project "The Glass Harbor"
  — 3 chapters of prose, 4 linked characters, 1 world location, 6-node board.
- Dockerfile + compose wiring for the server runtime.

Acceptance: seed project opens with 3 chapters, 4 linked characters, 1 board.

apps/web/src/store/settings.ts

@@ -0,0 +1,67 @@
+import { create } from "zustand";
+import { applyTheme, type ThemeId } from "@pubscript/ui";
+
+export type Density = "compact" | "comfortable";
+
+export interface AppSettings {
+  theme: ThemeId;
+  accentColor: string;
+  density: Density;
+  fontSize: number;
+  showLineNumbers: boolean;
+  wordCountGoal: number;
+  autoSave: boolean;
+}
+
+export const DEFAULT_SETTINGS: AppSettings = {
+  theme: "ink",
+  accentColor: "#7c8bf5",
+  density: "comfortable",
+  fontSize: 15,
+  showLineNumbers: true,
+  wordCountGoal: 80_000,
+  autoSave: true,
+};
+
+const STORAGE_KEY = "pubscript.settings.v1";
+
+function loadSettings(): AppSettings {
+  try {
+    const raw = localStorage.getItem(STORAGE_KEY);
+    if (!raw) return { ...DEFAULT_SETTINGS };
+    const parsed = JSON.parse(raw) as Partial<AppSettings>;
+    return { ...DEFAULT_SETTINGS, ...parsed };
+  } catch {
+    return { ...DEFAULT_SETTINGS };
+  }
+}
+
+export interface SettingsStore extends AppSettings {
+  set: (patch: Partial<AppSettings>) => void;
+  setTheme: (theme: ThemeId) => void;
+  reset: () => void;
+}
+
+export const useSettings = create<SettingsStore>((set, get) => {
+  const initial = loadSettings();
+  // Apply the persisted theme on boot.
+  applyTheme(initial.theme);
+
+  return {
+    ...initial,
+    set: (patch) => {
+      const next = { ...get(), ...patch };
+      localStorage.setItem(STORAGE_KEY, JSON.stringify(next));
+      set(next);
+    },
+    setTheme: (theme) => {
+      applyTheme(theme);
+      get().set({ theme });
+    },
+    reset: () => {
+      localStorage.removeItem(STORAGE_KEY);
+      applyTheme(DEFAULT_SETTINGS.theme);
+      set({ ...DEFAULT_SETTINGS });
+    },
+  };
+});