chore: remove dead code, unused CSS, unused components, and clean up git tracking

- Remove storage/logs/ and prod.log from git tracking; add to .gitignore
- Remove unused AvatarCarousel and ArticleSlider components
- Remove unused SkeletonTable export from ui.tsx
- Remove unused ChevronDown import from admin layout
- Remove 13 unused CSS classes (icon-base, nav-*, navigation-icon*, .app.dark,
  text-body, transition-base, card-base, admin-info-grid, .coin.*)
- Remove duplicate translation keys (openMenu/closeMenu in en.json)
- Fix admin-bans to use Prisma-generated bans_type enum
- Create shared AdminPageHeader component and formatDate utility
- Add logger and generateRequestId for structured logging
- All 58 tests pass, typecheck clean, build succeeds

src/lib/format-date.ts

@@ -0,0 +1,9 @@
+/** Format a Date as 'YYYY-MM-DD HH:MM:SS' — used across admin and radio pages. */
+export function formatDateTime(d: Date | null | undefined): string {
+  return d ? d.toISOString().slice(0, 19).replace("T", " ") : "";
+}
+
+/** Format a Date as 'YYYY-MM-DD' — used across radio list pages. */
+export function formatDate(d: Date | null | undefined): string {
+  return d ? d.toISOString().slice(0, 10) : "";
+}