feat(web): SPA shell — gate, settings, today placeholder

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

web/tsconfig.json

@@ -0,0 +1,13 @@
+{
+  "compilerOptions": {
+    "strict": true,
+    "jsx": "react-jsx",
+    "module": "ESNext",
+    "moduleResolution": "bundler",
+    "target": "ES2022",
+    "lib": ["ES2022", "DOM", "DOM.Iterable"],
+    "skipLibCheck": true,
+    "noEmit": true
+  },
+  "include": ["src"]
+}