Add database package with Drizzle schema

Postgres schema via Drizzle ORM for agents, goals, issues, projects,
and activity log tables. Includes migration runner, seed script,
and Drizzle config.

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

packages/db/package.json

@@ -0,0 +1,27 @@
+{
+  "name": "@paperclip/db",
+  "version": "0.0.1",
+  "private": true,
+  "type": "module",
+  "exports": {
+    ".": "./src/index.ts",
+    "./*": "./src/*.ts"
+  },
+  "scripts": {
+    "typecheck": "tsc --noEmit",
+    "generate": "drizzle-kit generate",
+    "migrate": "tsx src/migrate.ts",
+    "seed": "tsx src/seed.ts"
+  },
+  "dependencies": {
+    "@paperclip/shared": "workspace:*",
+    "drizzle-orm": "^0.38.4",
+    "postgres": "^3.4.5"
+  },
+  "devDependencies": {
+    "drizzle-kit": "^0.30.4",
+    "tsx": "^4.19.2",
+    "typescript": "^5.7.3",
+    "vitest": "^3.0.5"
+  }
+}