Add webapp subproject (Vite + TypeScript + Web Components)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

webapp/vite.config.ts

@@ -0,0 +1,14 @@
+import { defineConfig } from 'vite'
+
+export default defineConfig({
+  server: {
+    proxy: {
+      '/v1': 'http://localhost:8080',
+      '/login': 'http://localhost:8080',
+      '/logout': 'http://localhost:8080',
+    },
+  },
+  build: {
+    outDir: 'dist',
+  },
+})