feat: groups bulk management, single-group panel, UX improvements

- Add Bulk Group Actions to Manage tab: set picture (URL or file upload),
  name, description, settings, disappearing messages across multiple groups
- Context-aware single-group panel (Participants, Invite Link, Leave Group)
  appears automatically when exactly 1 group is selected
- Gear icon in Browse & Send now pre-selects that group in Manage tab
- "Manage Selected Groups" button in Browse & Send passes selection to Manage tab
- Fix group update endpoints: correct Evolution API v2 route names and
  move groupJid from query param to request body
- Scheduled jobs: clicking card body toggles details panel
- Scheduled jobs: uniform button widths
- Group list max-height increased to 60vh

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: Eran