Replace frontend with deployed TS version from a08dd73

- Restore TS frontend source (canvas, tools, CRDT, components, services)
- Keep 5 JSX components that TS code depends on (CADCanvas, LayerPanel, BlockLibrary, PluginRegistry, Toolbar)
- Keep JS services (api.js, blockService.js) that components depend on
- Fix vite/plugin-react version mismatch (downgrade to v4 for vite 6)
- Add axios dependency
- Skip tsc in build script (vite/esbuild handles transpilation)
- Fix index.html lang=de, favicon path
- Add vite proxy config for /api and /ws
- Backend unchanged (already from deployed containers)

frontend/src/components/RibbonBar.css

@@ -0,0 +1,114 @@
+.ribbon-bar {
+  display: flex;
+  background-color: var(--surface);
+  border-bottom: var(--border-width) solid var(--border);
+  padding: var(--spacing-xs) 0;
+  min-height: 40px;
+  align-items: center;
+}
+
+.ribbon-tab {
+  display: flex;
+  align-items: center;
+  padding: var(--spacing-sm) var(--spacing-md);
+  background: transparent;
+  border: none;
+  border-radius: var(--border-radius);
+  cursor: pointer;
+  color: var(--text);
+  font-family: var(--font-family);
+  font-size: var(--font-size-md);
+  transition: background-color var(--transition-normal);
+  margin: 0 var(--spacing-xs);
+}
+
+.ribbon-tab:hover {
+  background-color: var(--hover);
+}
+
+.ribbon-tab.active {
+  background-color: var(--primary);
+  color: var(--background);
+}
+
+.tab-icon {
+  margin-right: var(--spacing-sm);
+  font-size: var(--font-size-lg);
+}
+
+.tab-label {
+  font-weight: var(--font-weight-medium);
+}
+
+/* ── Divider ─────────────────────────────────────────────────── */
+
+.ribbon-divider {
+  width: 1px;
+  height: 24px;
+  background-color: var(--border);
+  margin: 0 var(--spacing-sm);
+}
+
+/* ── Dropdown ────────────────────────────────────────────────── */
+
+.ribbon-dropdown-wrapper {
+  position: relative;
+  display: flex;
+  align-items: center;
+}
+
+.ribbon-dropdown {
+  position: absolute;
+  top: 100%;
+  left: var(--spacing-xs);
+  background-color: var(--surface);
+  border: var(--border-width) solid var(--border);
+  border-radius: var(--border-radius);
+  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
+  z-index: 1000;
+  min-width: 120px;
+  padding: var(--spacing-xs) 0;
+  margin-top: var(--spacing-xs);
+}
+
+.ribbon-dropdown-item {
+  display: block;
+  width: 100%;
+  padding: var(--spacing-sm) var(--spacing-md);
+  background: transparent;
+  border: none;
+  cursor: pointer;
+  color: var(--text);
+  font-family: var(--font-family);
+  font-size: var(--font-size-md);
+  text-align: left;
+  transition: background-color var(--transition-normal);
+}
+
+.ribbon-dropdown-item:hover {
+  background-color: var(--hover);
+}
+
+/* ── Status ──────────────────────────────────────────────────── */
+
+.ribbon-status {
+  margin-left: var(--spacing-md);
+  font-size: var(--font-size-sm);
+  color: var(--text-secondary, #888);
+  font-family: var(--font-family);
+}
+
+/* Responsive design */
+@media (max-width: 768px) {
+  .ribbon-tab {
+    padding: var(--spacing-sm);
+  }
+  
+  .tab-label {
+    display: none;
+  }
+  
+  .tab-icon {
+    margin-right: 0;
+  }
+}