feat: refactor clinic management into a dedicated settings tab

- Removed MyClinicPage and redirected its functionality to a new ClinicDoctorsPage.
- Created ClinicDoctorsManager component for managing doctors and invitations within the settings layout.
- Updated backend permissions to allow clinic owners to detach doctors, alongside admins.
- Adjusted API documentation to reflect new permission structure.
- Updated tests to cover new functionality and permissions.
- Modified sidebar and settings menu to reflect the new structure and role-based visibility.

docs/api/clinic.md

@@ -316,7 +316,7 @@ Get doctors associated with a clinic.
 
 Detach a doctor from a clinic. This removes the clinic↔doctor link only (the `clinic_doctors` association); it does **not** delete the doctor or change the doctor's own `active` appointment flag.
 
-**Permission:** `ROLE_ADMIN`
+**Permission:** `AUTH` — the caller must be `ROLE_ADMIN` **or** the owner of this clinic (`ROLE_CLINIC` whose user owns `clinicUuid`). Any other authenticated user gets `403`.
 
 ### Path Parameters
 | Param | Type | Description |
@@ -332,6 +332,7 @@ Detach a doctor from a clinic. This removes the clinic↔doctor link only (the `
 ### Errors
 | Code | HTTP | Description |
 |------|------|-------------|
+| `ERR_ACCESS_DENIED` | 403 | Caller is neither an admin nor the clinic owner |
 | `ERR_VALIDATION_002` | 404 | Clinic not found |
 | `ERR_NOT_FOUND_001` | 404 | Doctor not found, or doctor not linked to this clinic |