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/StatusBar.tsx

@@ -0,0 +1,39 @@
+import React from 'react';
+import './StatusBar.css';
+
+const StatusBar: React.FC = () => {
+  // Mock status data
+  const coordinates = { x: 10.5, y: 20.3 };
+  const snapEnabled = true;
+  const activeLayer = 'Layer 1';
+  const units = 'mm';
+  
+  return (
+    <div className="status-bar" role="status" aria-label="Application Status">
+      <div className="status-section coordinates">
+        <span className="status-label">Coordinates:</span>
+        <span className="status-value">X: {coordinates.x}, Y: {coordinates.y}</span>
+      </div>
+      <div className="status-section snap">
+        <span className="status-label">Snap:</span>
+        <button 
+          className={`toggle-button ${snapEnabled ? 'enabled' : 'disabled'}`}
+          aria-pressed={snapEnabled}
+          aria-label={snapEnabled ? 'Snap enabled. Click to disable' : 'Snap disabled. Click to enable'}
+        >
+          {snapEnabled ? 'ON' : 'OFF'}
+        </button>
+      </div>
+      <div className="status-section layer">
+        <span className="status-label">Layer:</span>
+        <span className="status-value">{activeLayer}</span>
+      </div>
+      <div className="status-section units">
+        <span className="status-label">Units:</span>
+        <span className="status-value">{units}</span>
+      </div>
+    </div>
+  );
+};
+
+export default StatusBar;