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/update_profile.md

@@ -1,24 +1,59 @@
 # Update Profile
 
-Update the current user's profile information.
+Update user profile information. Supports both self-edit and admin modes.
+
+**Endpoints**:
+- Self-edit: `PUT /api/auth/profile`
+- Admin edit: `PUT /api/auth/profile/:id`
 
-**Endpoint**: `PUT /api/auth/profile`
 **Auth**: Required
 **Content-Type**: `application/json`
 
-## Request Body
+## Self-Edit Mode
+
+Users can update their own profile. All fields are optional.
+
+### Request Body
 
 | Field | Type | Required | Description |
 |--------|------|-----------|-------------|
+| username | string | No | New username (must be unique, 3-50 chars) |
+| email | string | No | New email (must be unique, valid format) |
 | first_name | string | No | User's first name |
 | last_name | string | No | User's last name |
+| theme | string | No | Theme preference |
 
 ### Example Request
 
 ```json
 {
+  "username": "newusername",
+  "email": "newemail@example.com",
   "first_name": "John",
-  "last_name": "Smith"
+  "last_name": "Smith",
+  "theme": "dracula"
+}
+```
+
+## Admin Mode
+
+Admins can update any user by providing the user ID in the URL. Additionally supports role changes.
+
+**URL Parameter**: `:id` - Target user's UUID
+
+### Additional Request Body Fields (Admin Only)
+
+| Field | Type | Required | Description |
+|--------|------|-----------|-------------|
+| role | string | No | New role: "user" or "admin" |
+
+### Example Admin Request
+
+```json
+{
+  "username": "newusername",
+  "email": "newemail@example.com",
+  "role": "admin"
 }
 ```
 
@@ -31,7 +66,7 @@ Update the current user's profile information.
   "username": "john",
   "first_name": "John",
   "last_name": "Smith",
-  "theme": "tokyo-night",
+  "theme": "dracula",
   "role": "user",
   "max_devices": 10,
   "created_at": "2026-01-31T10:00:00Z"
@@ -42,5 +77,8 @@ Update the current user's profile information.
 
 | Code | Description |
 |------|-------------|
-| 400 | Invalid input data |
+| 400 | Invalid input data or invalid role |
 | 401 | Invalid or expired token |
+| 403 | Admin access required (admin mode only) |
+| 404 | User not found (admin mode only) |
+| 409 | Username or email already taken |