feat: US-002 — SQLite + Drizzle ORM schema and migrations

- Install better-sqlite3 + drizzle-orm as runtime deps; drizzle-kit + @types/better-sqlite3 as devDeps
- Define 5 tables in src/main/db/schema.ts: clients, projects, tasks, checkpoints, notes
- All IDs are TEXT (UUID); types inferred via InferSelectModel/InferInsertModel
- initDb() in src/main/db/index.ts opens adiuva.db at app.getPath('userData'), runs CREATE TABLE IF NOT EXISTS (non-destructive push), enables WAL mode
- Call initDb() in main process app ready handler
- Externalize better-sqlite3 in vite.main.config.mts; add AutoUnpackNativesPlugin to forge.config.ts
- Add drizzle.config.ts for drizzle-kit CLI support

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

package.json

@@ -26,6 +26,7 @@
     "@electron-forge/plugin-vite": "^7.11.1",
     "@electron/fuses": "^1.8.0",
     "@tanstack/router-vite-plugin": "^1.161.1",
+    "@types/better-sqlite3": "^7.6.13",
     "@types/electron-squirrel-startup": "^1.0.2",
     "@types/react": "^19.2.14",
     "@types/react-dom": "^19.2.3",
@@ -33,6 +34,7 @@
     "@typescript-eslint/parser": "^5.62.0",
     "@vitejs/plugin-react": "^5.1.4",
     "autoprefixer": "^10.4.24",
+    "drizzle-kit": "^0.31.9",
     "electron": "40.6.0",
     "eslint": "^8.57.1",
     "eslint-plugin-import": "^2.32.0",
@@ -43,8 +45,10 @@
   },
   "dependencies": {
     "@tanstack/react-router": "^1.161.1",
+    "better-sqlite3": "^12.6.2",
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
+    "drizzle-orm": "^0.45.1",
     "electron-squirrel-startup": "^1.0.1",
     "framer-motion": "^12.34.2",
     "lucide-react": "^0.575.0",