Retrieve invitations with comprehensive filtering capabilities including date-based filtering.
  
  **Key Features:**
  - **Date Filtering**: Use `openSinceDays` and/or `openUntilDays` to filter invitations by creation date
  - **Text Search**: Filter by email, first name, last name, or business name with partial matching
  - **Pagination**: Built-in pagination with configurable limits and offsets
  - **Sorting**: Sort results by various fields (creation date, name, etc.)
  
  **Date Filter Examples:**
  - `openSinceDays=30`: Get invitations from the last 30 days (30 days or newer)
  - `openUntilDays=90`: Get invitations older than 90 days
  - `openSinceDays=20&openUntilDays=25`: Get invitations between 20-25 days old (time window)
  
  **Combined Filter Examples:**
  - `openSinceDays=30&firstName=John`: Recent invitations for users named John
  - `openUntilDays=180&businessName=Acme`: Older invitations for Acme company
  - `openSinceDays=20&openUntilDays=25&limit=20`: Invitations in 20-25 day window with pagination
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