M7: portfolio polish and final acceptance

Automated migrations on container startup (backend/entrypoint.sh), scripted n8n workflow activation (make n8n-setup), Playwright E2E test covering the full 9-step demo script (verified passing against the live stack, including the previously-unverified 360px responsive layout), evidence screenshots of all main pages, architecture diagram, and artifacts/evidence/final-summary.md with commit/commands/test counts/RAGcore and n8n evidence/MCP sample calls/known limitations/portfolio wording. Verified the complete clean-checkout path from a genuinely wiped-volumes state: automatic migrations, seed, 66 backend tests passing, and a live S1 return round-tripped through a freshly-activated n8n instance. Added .gitattributes to force LF line endings on shell scripts, preventing a real cross-platform breakage of entrypoint.sh's shebang.

frontend/package.json

@@ -7,7 +7,8 @@
     "dev": "vite --host 0.0.0.0",
     "build": "tsc -b && vite build",
     "preview": "vite preview --host 0.0.0.0",
-    "lint": "tsc -b --noEmit"
+    "lint": "tsc -b --noEmit",
+    "test:e2e": "playwright test"
   },
   "dependencies": {
     "react": "18.3.1",
@@ -15,6 +16,7 @@
     "react-router-dom": "7.18.2"
   },
   "devDependencies": {
+    "@playwright/test": "1.62.1",
     "@types/react": "18.3.12",
     "@types/react-dom": "18.3.1",
     "@vitejs/plugin-react": "4.3.4",