feat: implement comprehensive admin-only management commands

Overview

This Merge Request introduces a new admin command group to the CLI, providing a unified interface for administrative tasks that were previously only available via direct API calls or the backend database.

Changes

• New Admin Command Group Added a modular sub-command structure in src/corpus_client_cli/admin.py:

  • admin roles: List, get, and create system roles
  • admin users: Paginated listing of all registered users
  • admin auth: Administrative utilities, including remote password resets
  • admin categories: Full lifecycle management (list pending, create, approve, reject, and delete)
  • admin history: Management of pending history restore operations

• Standardized Admin Requests Implemented a private _admin_request helper to handle:

  • Automatic authentication state verification
  • Consistent header management (Authorization: Bearer <token>)
  • Standardized error reporting and JSON output rendering using rich

• CLI Integration Registered the admin sub-app in the main corpus-client entry point

• Testing Added tests/test_admin_commands.py covering all new endpoints and edge cases (e.g., missing authentication)

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How to Test

1. Ensure you are logged in with an account that has admin privileges:

   corpus-client login

2. Test role listing:

   corpus-client admin roles list

3. Test category moderation (if pending categories exist):

   corpus-client admin categories list-pending

4. Verify that non-admin accounts receive the appropriate 403 Forbidden error when attempting these commands.

Related Issues

Closes #38 (closed)