Preserve text formatting (RTF/HTML) when pasting older clippings

[MiMoHo]

Summary

Flycut has always stored and pasted plain text only — pasting any clipping through the bezel, menu, or search window strips all formatting. This adds formatting preservation:

• On capture, the RTF and HTML representations of a text clipping are read (if present) and stored alongside the plain text
• On paste, the rich types are declared in addition to the plain string — rich text editors keep bold, fonts, links, and colors; plain-text targets are completely unaffected
• Works for the bezel, the menu, and the search window paste paths
• Rich data persists through the existing NSUserDefaults store and survives restarts

Design / privacy considerations

• Rich data is only captured after the existing shouldSkip: checks pass, so concealed/transient clippings (password managers) never have their rich representations read
• Capped at 1 MB per representation so a giant styled clipping can't bloat the store; RTFD (embedded images) is deliberately not captured
• Loading validates the shape of persisted rich data (string keys → NSData values) before restoring it, so a corrupted plist can't inject unexpected types
• New preserveTextFormatting default (ON), documented in help.md, opt-out via defaults write com.generalarcade.flycut preserveTextFormatting -bool NO — happy to wire a preferences checkbox if you'd like one in the panel
• Display strings, search, and dedup still operate on the plain text, so behavior there is unchanged

Testing

All changed files pass clang -fsyntax-only against the macOS SDK with no new diagnostics versus master. I could not run a full xcodebuild locally (no full Xcode on this machine), so please give it a CI build/manual smoke test: copy styled text from e.g. Safari or TextEdit, copy something else, then paste the older clipping into TextEdit (formatting kept) and into a terminal (plain text as before).

🤖 Generated with Claude Code