Add guided custom build wizard

[ODevStudio]

Summary

• Add an optional Wizard beside HDS Updater using matching navigation styling.
• Number and highlight Firmware, Features, Approved plugins and Build summary; include My scales only for WiFi.
• Add inline explanations, Back/Next/Finish/Close controls, Escape dismissal and focus restoration.
• Keep build requests, saving, assignment and installation explicitly user-controlled.
• Include the locally reviewed Step 5 spacing fix. No firmware or Worker runtime changes.

Validation

• 18 Node tests passed, including a new wizard navigation regression test.
• Local Playwright checks passed at 1280px and 390px: WiFi/USB traversal, mode switching, Back, Escape, focus restoration, Step 5 spacing and horizontal overflow.
• Browser API responses were mocked; no production writes or hardware operations.
• User reviewed the local UI and approved creating this PR.
• git diff --check passed.