v2026-04-10-00

• chore: release v2026-04-10-00
• fix: background mode must not create window; guard autostart OSError in dialog
• fix: review findings — autostart_check guard, error handling, binary path
• ux: show setup prompt to existing users upgrading without autostart
• ux: first-run prompt shows two pre-checked opt-out checkboxes
• feat: launch at login via XDG autostart (#97)
• docs: update download links for v2026-04-09-00