VSN-2825/ Fix: Form loading issues & UI/UX improvements on Sections (Agents, Clients, Users)

This merge request includes multiple fixes and improvements across different sections:

🔧 Section - Collaborators (Agents)

• Fixed issue where the agent modification form was not loading existing data correctly:
  • Agency
  • Department
  • Password

👤 Section - Clients

• Updated behavior when double-clicking on a client (Tab navigation):
  • The Responsable tab is now read-only (non-editable)
  • The Documents tab is now read-only (non-editable)

👥 Section - Users

• Added missing search functionality in the Department column to improve filtering and usability.

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🧪 Impact

• Improves data consistency in edit forms
• Enhances UI/UX for client detail navigation
• Restores expected filtering capability in user management