Apache reverse proxy for webapp, UI improvements

- Move Flask to localhost:9010, Apache serves port 9009 with static file
  handling and reverse proxy to fix intermittent asset loading on remote clients
- Add "PXE Manager" branding beneath logo in sidebar
- Increase code editor size (startnet.cmd and unattend XML) to 70vh
- Add test-lab.sh for full lab VM testing

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

webapp/templates/startnet_editor.html

@@ -6,7 +6,9 @@
   .cmd-editor {
     font-family: 'Consolas', 'Courier New', monospace;
     font-size: 0.9rem;
-    min-height: 400px;
+    min-height: 600px;
+    height: 70vh;
+    resize: vertical;
     background-color: #1e1e1e;
     color: #d4d4d4;
     border: 1px solid #333;