docs(engineering): add project audit report and improvement plan

This commit introduces a comprehensive engineering audit report for the Tootaio Studio project. The report is structured into documents covering architecture, code quality, performance, security, CI/CD, and
observability. It also includes a phased improvement roadmap and a set of `.patch` files to apply immediate fixes for content schemas, package scripts, and CI configuration.

docs/20251106/patches/0003-github-actions-ci.patch

@@ -0,0 +1,34 @@
+diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
+new file mode 100644
+--- /dev/null
++++ b/.github/workflows/ci.yml
+@@
+name: CI
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Setup Node
+        uses: actions/setup-node@v4
+        with:
+          node-version: 20
+          cache: 'pnpm'
+      - name: Enable Corepack
+        run: corepack enable
+      - name: Install dependencies
+        run: pnpm i --frozen-lockfile
+      - name: Lint
+        run: pnpm lint
+      - name: Typecheck
+        run: pnpm typecheck
+      - name: Build
+        run: pnpm build