chore: cleanup TypeScript, update docs, scripts, Dockerfile

- Delete all frontend TypeScript source (src/, index.html, package.json, etc.)
- Move static assets to frontend/static/ (style.css, manifest.json)
- Update scripts/build and scripts/test (no npm steps)
- Update Dockerfile (no frontend build step)
- Update README.md and AGENTS.md for Hyperbole stack

frontend/static/manifest.json

@@ -0,0 +1,13 @@
+{
+  "name": "Sis",
+  "short_name": "Sis",
+  "description": "Shared household chore tracker",
+  "start_url": "/",
+  "display": "standalone",
+  "theme_color": "#fff9e6",
+  "background_color": "#fff9e6",
+  "icons": [
+    { "src": "/icon-192.png", "sizes": "192x192", "type": "image/png" },
+    { "src": "/icon-512.png", "sizes": "512x512", "type": "image/png" }
+  ]
+}