v0.5.0

AirPDF 0.5.0

Annotation tools arrive in full: ink, sticky notes, an eraser, colour palettes, and a thickness
control, with undo and redo covering all of them.

• Draw with Ctrl+Shift+K or the pen. The stroke under the pointer is the colour and thickness it
  will keep; the arrow beside the pen opens the colours and a live thickness sample.
• Erase any markup with the eraser: one drag is one undo step. Esc leaves the eraser as well as
  the pen.
• Add sticky notes and remove annotations from the page menu; click a note to read it.
• The pen and its palette arrow form one control, with the current colour under the nib.
• Undo and redo keep the last 100 markup edits and restore the exact colour of erased highlights
  and strokes instead of bringing them back black.
• Text selection, drawing, and erasing are mutually exclusive; switching to a tool clears the
  selection.
• One PDF is one tab: opening a file that is already open focuses its tab, so saving no longer
  fails because a second session holds the file.
• Closing a tab reliably returns to Home, and reopening the same file from the recent list
  renders its pages at the remembered position instead of showing a blank document.

Unsigned Windows and macOS installers stay withheld; Windows uses the Microsoft Store, and macOS
and Linux ship portable archives.

202 tests pass.