feat(web): Projektgerüst, Router, Grundlayout

Vite + TypeScript ohne UI-Framework in web/, exakte Versionen, History-Router
(matchRoute, navigate, startRouter mit Cleanup, a[data-link], popstate),
Grundlayout mit Kopfzeile, Fußzeile und Platzhalterseiten.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/tsconfig.json

@@ -0,0 +1,14 @@
+{
+  "compilerOptions": {
+    "target": "ES2022",
+    "lib": ["ES2022", "DOM", "DOM.Iterable"],
+    "module": "ESNext",
+    "moduleResolution": "bundler",
+    "strict": true,
+    "noEmit": true,
+    "isolatedModules": true,
+    "skipLibCheck": true,
+    "types": ["vite/client"]
+  },
+  "include": ["src", "vite.config.ts"]
+}