Release 1.3.0: new first-run permission flow

[StevenACZ]

Summary

• First launch asks for Accessibility in one setup window with a short reason.
• Open Settings shows a guide inside System Settings that follows its window every frame and lets you drag Encaje's icon into the list; the setup window comes back to the front after the grant.
• Once access is on, a short welcome plays and closes by itself. Macs where Encaje is already set up skip it.
• The old welcome window and Settings assistant are removed.
• Version 1.3.0, build 18.

Verification

• make check passes with 91 tests.
• First run walked from zero permissions on a test Mac.