Blackboard Text 2.3.0

Short links you can turn off, page search, and a round of safety fixes.
Includes the work prepared as 2.2.1.

Added

• Short links. Create short link in the share dialog uploads one copy
  of the selected page to a small Cloudflare service and gives you a short
  address. Nothing else in your workspace leaves the browser.
• Disable a short link later from Shared links from this browser; it then
  stops opening. Full links, with nothing uploaded, remain the default.
• Find a page in Settings, or Ctrl/⌘ K, searches page names and text.
• Page actions: sharing, TXT and Markdown export, recovery, drawing redo
  and keyboard help in one place.
• Import can add pages instead of replacing the workspace; pages with matching
  IDs can be kept as copies or skipped.
• Browse recovery history previews the seven local snapshots and recovers
  single pages as new pages.
• Shared notes keep their original board and add Readable text and zoom.

Fixed

• Security: the reader blocks dangerous link protocols and remote media in
  shared notes.
• Save failures are shown instead of passing silently, and the update Reload
  waits until your latest change is saved.
• Strokes from older versions keep their thickness after migration.
• Backup and confirmation dialogs are real modal dialogs; shortcuts no longer
  reach the editor behind them.
• Read-only tabs can switch pages and still manage shared copies.
• Reset to defaults uses the correct theme; opening the colour picker no longer
  changes the colour by itself.
• Reader layout fixes for scaled boards and drawing alignment.
• Very long notes cap the drawing bitmap at 8 million pixels to keep memory
  bounded. Note data is never cut.