Migrate the entire admin section from the dark guild-* Tailwind theme
to the zine design system (dashed borders, CSS custom properties,
Brygada 1918 + Commit Mono, cream/dark mode palette).
- Replace admin top-nav layout with sidebar matching default layout
- Reskin dashboard, members, events, series management pages
- Reskin events/create and series/create form pages
- Add dev-only test login endpoint (GET /api/dev/test-login)
- Redirect duplicate admin/dashboard.vue to /admin
- Update CLAUDE.md design system docs
Wrap auth-dependent sidebar navigation and meta in ClientOnly with
SSR fallback slots to prevent hydration mismatch that caused all
authenticated nav links to point to wrong pages. Fix admin events
page crash by replacing empty string USelect values with 'all'.
Standardizes color values and styling using the new tokens:
- Replaces hardcoded colors with semantic variables
- Updates background/text/border classes for light/dark mode
- Migrates inputs to UInput/USelect/UTextarea components
- Removes redundant style declarations
