feat: add remote issue template support with dynamic TUI fields
- Configure issue_template in pad.toml (default: .github/ISSUE_TEMPLATE/daily-update.yml)
- Fetch and parse issue templates remotely from GitHub
- Generate TUI fields dynamically from template structure
- Embed hidden field ID markers (<!-- pad:id:... -->) in issue bodies
- Handle template changes: carry over orphaned fields to synthetic section
- Add loading spinners for all remote operations
- Generate issue titles from template title field with date placeholders
- Support date formats: YYYY/MM/DD, YYYY-MM-DD, MM/DD/YYYY, DD/MM/YYYY
- Fallback to legacy title format when template has no title
- Update bundled report workflow to parse by field IDs