Separate JSON API backend (vm_api.py) + React+TanStack frontend scaffold

- vm_api.py: pure FastAPI JSON API on :8098 with CORS
- vm-api.service: systemd unit for API (replaces inline HTML vm_web.py for frontend)
- vm_web.py: kept intact as fallback; Apache now proxies /api/ -> :8098
- frontend/: Vite + React + TanStack Query scaffold
- Apache vhost updated: DocumentRoot -> frontend/dist, /api/ proxy, SPA fallback
- All original HTML pages still functional via :8099 during transition

frontend/node_modules/postcss/lib/document.js

@@ -0,0 +1,33 @@
+'use strict'
+
+let Container = require('./container')
+
+let LazyResult, Processor
+
+class Document extends Container {
+  constructor(defaults) {
+    // type needs to be passed to super, otherwise child roots won't be normalized correctly
+    super({ type: 'document', ...defaults })
+
+    if (!this.nodes) {
+      this.nodes = []
+    }
+  }
+
+  toResult(opts = {}) {
+    let lazy = new LazyResult(new Processor(), this, opts)
+
+    return lazy.stringify()
+  }
+}
+
+Document.registerLazyResult = dependant => {
+  LazyResult = dependant
+}
+
+Document.registerProcessor = dependant => {
+  Processor = dependant
+}
+
+module.exports = Document
+Document.default = Document