feat: backend infra setup with prisma, services, and apis

- Added Prisma schema with Asset, Character, Equipment, Generation, Category models
- Configured SQLite with LibSQL adapter
- Implemented Service layer with unit tests
- Implemented API layer with Hono and integration tests
- Added static file serving for assets
- Configured CI/CD with GitHub Actions
- Added Developer Guide (AGENTS.md)

.github/workflows/ci.yml

@@ -0,0 +1,39 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+      - uses: oven-sh/setup-bun@v1
+        with:
+          bun-version: latest
+
+      - name: Install dependencies
+        run: bun install
+
+      - name: Generate Prisma Client
+        run: bun --bun run prisma generate
+        env:
+          DATABASE_URL: 'file:./test.db'
+
+      - name: Lint
+        run: bun run lint
+
+      - name: Format Check
+        run: bun run format:check
+
+      - name: Typecheck
+        run: bun run typecheck
+
+      - name: Run Tests
+        run: bun run test
+        env:
+          DATABASE_URL: 'file:./test.db'