NeXroll v2.0.0-beta.3

Docker feedback fixes plus a major dashboard refinement round. Upgrade-safe: existing installs keep all data and settings.

Fixed

Community prerolls index no longer wiped by Docker updates. The index now lives on the /data volume; previously every image update reset it to "No index." Rebuild it once after this update and it will persist from then on.
NeX-Up trailers no longer show up twice (once Uncategorized). The library scanner was also indexing the trailer storage folder; it now leaves NeX-Up's files alone and automatically removes the duplicate entries it had created on the next scan.
Dashboard scroll and text selection no longer reset every few seconds - two background updaters were re-rendering the whole app continuously. Noticeably snappier UI overall.
Tile heights are now stable and content-fitting - tiles no longer grow when moved in edit mode, clip their content, or show stray scrollbars.
Several icon buttons that rendered as empty boxes (Edit category, Edit preroll, Close on previews) have their icons back.
Native time/date pickers and dropdowns finally follow dark mode.
Plex server name now shows on the Servers tile.

Dashboard redesign, round 2:
- Unified tile design with richer at-a-glance info: server address, external/mapped preroll count, last-added time, scheduler timezone and "firing today", Now/Next schedule rows, community index freshness and size, NeX-Up trailer storage bar.
- Every tile header has an action button - jump to the relevant page, Stop/Start the scheduler, or Preview what's currently applied.
- Quick Actions now live on the dashboard in a toolbar above the tiles (Rebuild Thumbs, Refresh Data, NeX-Up Sync, Scan Files, Rebuild Index, Backup DB, Check Updates). The separate Quick Actions page is gone.
- Video Quality tile redesigned with a clean distribution bar and percentage legend - and the old charting library was removed entirely, making the app 21% smaller and faster to load.
- Upcoming Schedules scrolls with a fade hint instead of stretching.
Schedule time pickers gained one-click presets (9:00 AM, 12:00 PM, 6:00 PM, 9:00 PM, end-of-day) in the create and edit forms.
The loading screen now greets you with a random theater pre-show line.

Feedback welcome - report anything odd on the issue tracker or Discord.