fix: move navigation code to early init, right after DOM refs

fix: remove DOMContentLoaded wrapper for immediate navigation init

fix: wrap page navigation in DOMContentLoaded and simplify logic

fix: correct page navigation display logic for detect page

debug: add console logging to page navigation for troubleshooting

feat: add About page with system spec link to web UI

fix: wire up VLM toggle in web UI (checkbox + JS + CSS)

feat: scale-invariant DINODense verifier path + remove CLIP prototype

feat: Zero-shot pattern detection pipeline for engineering BOM drawings