v0.2.0 - theme flag, preview scrolling and UX improvements

New features

• --theme flag to force light or dark palette (OSC 11 doesn't work inside tmux popups)
• Preview pane scrollable with J/K, shift+↓/shift+↑, and mouse wheel
• Preview pane shows first and latest exchange with model name tag
• Tmux windows auto-rename to session title (trimmed to 10 chars)
• Scrollbar in preview pane

Changed

• Flags use -- prefix instead of - (e.g. --tmux, --no-preview, --theme)
• Preview pane now shows first and latest message pairs (not just first)
• Preview pane truncation skips blank lines before counting content lines

Fixed

• Flag parsing rewritten to support --flag=value and --flag value syntax