v2.6.1

Bug fixes and improvements to the file viewer, inbox, home, and diff views.

File viewer (Repositories > Tree):
- Rewrote the file content view using UIViewRepresentable to fix long-standing
  layout issues. Line numbers are now pinned to the left and never scroll
  horizontally. Code content scrolls independently.
- Added syntax highlighting for Swift files via Splash, with plain monospaced
  rendering as a fallback for other file types.
- Added a bottom toolbar with Share, Copy All, and Word Wrap actions.
- Fixed horizontal scrolling when wrap is off -- content width is now correctly
  derived from the longest line.
- Fixed horizontal scroll view remaining gesture-active when wrap is on.

Inbox:
- Added Mark All Read button to the navigation bar.
- Home screen inbox icon now uses fill state to indicate unread messages
  instead of a blue dot badge.
- Fixed unnecessary network request fired after marking all threads as read.
- Inbox now refreshes when returning from the background.
- Updated empty state copy to "You're up to date."

Home:
- Home dashboard now refreshes when the app returns to the foreground.
- Widget empty state redesigned across all three sizes using SF Symbols.

Diff view:
- Long diff lines are now horizontally scrollable instead of wrapping or
  clipping.
- Improved rendering performance on large diffs.

Settings:
- Fixed swipe actions toggle incorrectly accessing UserDefaults directly
  instead of going through the app's storage layer.