v1.0.0

feat: implement high-fidelity subtitle editor with elastic layout

- Created ParagraphEditor (NSTextView wrapper) for selection-aware editing
- Redesigned SubtitleEditorView to match SE side-by-side layout
- Implemented responsive vertical distribution for Start/Duration and tools
- Added real-time stats: Chars/second, line length, and total chars
- Upgraded italicizeSelected with smart toggle and range-based formatting
- Resolved Swift 6.1+ environment warnings and API deprecations
- Finalized professional margins and symmetrical UI alignment