Ghostty feature alignment

[daiimus]

Description

Track feature parity with upstream Ghostty where applicable to iOS. Ghostty has many features that could enhance Geistty's terminal experience.

Potential Areas

• Additional config options support
• Cursor styles and blinking
• Bell handling (visual bell, notification)
• OSC sequences (hyperlinks, color queries)
• Selection modes (block selection)
• Scrollback search improvements
• Notifications integration (OSC 9/777)

Approach

• Review upstream Ghostty features periodically
• Evaluate which features make sense for iOS
• Prioritize features that leverage existing C API
• Prefer Swift-side implementation over fork changes (Directive tmux session name grabbing (attaches to arbitrary sessions) #4)

Milestone

v0.4-polish — aligning with upstream after stability is achieved.