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.

packages/ui/package.json

@@ -0,0 +1,28 @@
+{
+  "name": "@pubscript/ui",
+  "version": "0.1.0",
+  "type": "module",
+  "main": "./src/index.ts",
+  "types": "./src/index.ts",
+  "exports": {
+    ".": "./src/index.ts",
+    "./package.json": "./package.json"
+  },
+  "scripts": {
+    "dev": "echo \"@pubscript/ui has no dev server\" (exit 0)",
+    "build": "tsc --noEmit",
+    "test": "vitest run",
+    "lint": "eslint .",
+    "typecheck": "tsc --noEmit"
+  },
+  "dependencies": {
+    "@pubscript/core": "workspace:*",
+    "react": "^19.0.0"
+  },
+  "devDependencies": {
+    "@types/node": "^22.10.2",
+    "@types/react": "^19.0.2",
+    "typescript": "^5.7.2",
+    "vitest": "^2.1.8"
+  }
+}