docs: update API documentation for consolidated user management

Add documentation for delete_user and reset_user_password endpoints.
Update update_profile to reflect consolidated endpoint. Remove obsolete
documentation for individual update operations. Add profile guide for
end-users. Update API_CONSOLIDATION_PLAN.md with implementation status.

docs/developer/api/users/delete_user.md

@@ -0,0 +1,46 @@
+# Delete User
+
+Delete a user account. Supports both self-deletion and admin deletion.
+
+**Endpoints**:
+- Self-deletion: `DELETE /api/auth/profile`
+- Admin deletion: `DELETE /api/auth/profile/:id`
+
+**Auth**: Required
+
+## Self-Deletion
+
+Users can delete their own account. This permanently removes the user and all associated data.
+
+**Endpoint**: `DELETE /api/auth/profile`
+
+## Admin Deletion
+
+Admins can delete any user account by providing the user ID in the URL.
+
+**URL Parameter**: `:id` - Target user's UUID
+
+**Endpoint**: `DELETE /api/auth/profile/:id`
+
+## Response (200 OK)
+
+```json
+{
+  "message": "account deleted"
+}
+```
+
+## Error Responses
+
+| Code | Description |
+|------|-------------|
+| 400 | Cannot delete the last admin |
+| 401 | Invalid or expired token |
+| 403 | Admin access required (trying to delete another user) |
+| 404 | User not found (admin mode only) |
+
+## Safety Rules
+
+- The last remaining admin cannot be deleted
+- Self-deletion requires the user to not be the last admin
+- Admin deletion is restricted to admin role only