Native sharing, event attachments, admin notifications, and sticky actions

✅ New functionalities

1. Native timeline sharing on supported devices, with a clearer sharing settings layout.
2. File attachments in rich-text event descriptions, with thumbnail previews in the editor and on shared pages.
3. Share public event URLs from event cards and copy deep anchor links with a confirmation tooltip.
4. Admin email notifications for confirmed sign-ups and new timeline subscriptions.
5. Storage tier enforcement with upgrade prompts when plan limits are reached.

🎛️ Improvements

1. Auto-scroll to the last updated event when opening a timeline.
2. Digest emails: “Happens today” / “Starts today” badges, attachment previews, and improved date headings.
3. Unified visibility badges; share and subscribe actions available on the event page.
4. Admin dashboard: storage file counts, subscriptions tab, persistent filters, and refined overview cards.
5. Sticky action bars on timeline, event, and board views; adaptive action labels when space allows.
6. Redesigned light glass navbar with updated logo and full-width top bar.
7. Fully clickable event cards; event form saves redirect to the event page with a loading spinner.

🐞 Bug Fixing

1. Sticky action bar positioning after mobile pull-to-refresh (including iOS PWA).
2. Unwanted horizontal scrolling and admin layout overflow on wide pages.
3. Case-insensitive email lookup at login.
4. Action Text migration order for event description attachments.
5. Compact/expanded action bar layout flash and navbar–title spacing.