feat: miller column browser, offline cache, search, breadcrumbs

- Dynamic miller column sizing with flexbox layout
- Root column (160px), middle slices (48px), active column (flex)
- Auto-scroll browser to rightmost column on navigation
- Offline indicator UI and IndexedDB cache integration
- /api/documents endpoint for client-side document caching
- Breadcrumb navigation in document content area
- FTS5 search with SQLite virtual table
- Client-side Mermaid and KaTeX rendering via CDN
- Deep sample content (advanced-topics/raft-deep-dive)
- Border removal (only search button keeps radius)
- Full viewport layout with proper borders between sidebar/content

apps/web/vite.config.ts

@@ -8,4 +8,21 @@ export default defineConfig({
     outDir: "dist",
     sourcemap: true,
   },
+  server: {
+    port: 5173,
+    proxy: {
+      "/api": {
+        target: "http://localhost:8080",
+        changeOrigin: true,
+      },
+      "/ws": {
+        target: "ws://localhost:8080",
+        ws: true,
+      },
+      "^/app$": {
+        target: "http://localhost:8080",
+        changeOrigin: true,
+      },
+    },
+  },
 });