CI: resolution sanity check (megapixels vs max_width×max_height)

[ch-bas]

Catch data-entry errors like a 4MP camera (2560×1440) mislabeled megapixels: 8 — hand-caught during the X-Spans import.

Add to scripts/build.js (alongside the #124 lint): for single-sensor cameras, warn/error if megapixels diverges from (max_width × max_height) / 1e6 beyond a tolerance (~±35%).

Must exempt multi-sensor cameras — panoramic / dual-lens / X-Spans legitimately use combined megapixels with single-stream max_width×max_height (e.g. SDT8C842 'Dual 8MP' → 16 MP). Detect via type (panoramic/dual-lens) or a 'Dual/Quad/x N' label, and skip those.

[ch-bas]

Concrete cleanup targets surfaced by the #177 streams backfill — 14 records carry only megapixels with no max_width/max_height, so a stream (and any resolution-derived logic) can't be built for them. Exactly the class a resolution sanity check should flag:

• ABUS (5): ipcb74615b, ppic46520, ppic46520w, ppic91000, ppic91520
• Speco (2): o4fdms1, o8fbms1
• Costar (7): av05cid-200, av05cid-201, av05cld-200, av10956dn-28, av12cfe-250, av16956dn-28, av4956dn-28

They need the pixel resolution backfilled from their datasheets. (Beyond the sanity check itself, worth a small data-fix pass.)