ui: align chat list and conversation buffer with mockups
Chat list (*signal*):
- Fringe ● now uses warning face (yellow), matching mockup's
unread indicator color
- Modeline trailing dashes extended for visual balance
Conversation buffer (*signal:NAME*):
- Compose prompt > changed from bold to link face (blue),
matching mockup's signal-blue prompt
- Attachment rendering: [attachment: ...] → [photo: ...]
- Modeline: (Signal Chat) → (Signal Chat Fill)
- Added header-line with key hints (RET send, M-RET newline,
C-c C-g refresh), matching mockup's discoverability goal
jbrechtel
71691a5261