v1.1 — Conversation Export

NEW: Export your ChatGPT conversations as TXT, PDF, or Word documents.
• Export the entire chat or only selected messages (Selection Mode)
• Each message includes the real timestamp from when it was sent
• Selection Mode automatically pairs question/answer when you mark one
• TXT export is free; PDF and Word require an active license

Performance & fixes:
• Optimized checkbox injection for chats with 300+ messages
• Fixed download flow on Firefox (uses blob URLs)
• Fixed popup not opening on first click in Firefox