Viewer redesign: unified camera_panel macro, new /viewer/<name> routes

Replace per-station viewer pages with 9 named views: scicam1-3,
teccam1-3, combo1-3. A single camera_panel Jinja2 macro renders the
unified snippet (large canvas + panner/explore + nested slot); combo
views inject the teccam panel into the scicam's nested slot via Jinja2
call blocks. Controls reduced to Min/Max + Reset + Auto-update; loop
controls (Exp/Start/Stop) shown only when device= is set in viewer.ini.
Nav dropdown updated to combo1/2/3. FitsViewer auto-update checkbox now
reads data-camera attribute for panel-scoped IDs. Pin numpy==2.3.5.

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