Add an optional way for users to support development:
- About card: tonal "Support development" button opening ko-fi.com
via ACTION_VIEW (no INTERNET permission), EN + DE strings
- F-Droid metadata: Donate field in self-hosted and official drafts
- README: short Support section with the Ko-fi link
No perks/rewards attached — kept as a plain donation link.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Code review flagged that F-Droid clients use Summary as the canonical
single-line app subtitle on the detail page; without it the slot would
fall back to the package id.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
