feat: UpdateUser implemented

api/paths/users-id.yaml

@@ -24,3 +24,79 @@ get:
       description: Request params are not correct
     '500':
       description: Unknown server error
+
+patch:
+  summary: Partially update a user account
+  description: |
+    Update selected user profile fields (excluding password). 
+    Password updates must be done via the dedicated auth-service (`/auth/`).
+    Fields not provided in the request body remain unchanged.
+  operationId: updateUser
+  parameters:
+    - name: user_id
+      in: path
+      required: true
+      schema:
+        type: integer
+        format: int64
+      description: User ID (primary key)
+      example: 123
+  requestBody:
+    required: true
+    content:
+      application/json:
+        schema:
+          type: object
+          properties:
+            avatar_id:
+              type: integer
+              format: int64
+              nullable: true
+              description: ID of the user avatar (references `images.id`); set to `null` to remove avatar
+              example: 42
+            mail:
+              type: string
+              format: email
+              pattern: '^[a-zA-Z0-9._-]+@[a-zA-Z0-9._-]+\\.[a-zA-Z0-9_-]+$'
+              description: User email (must be unique and valid)
+              example: john.doe.updated@example.com
+            nickname:
+              type: string
+              pattern: '^[a-zA-Z0-9_-]{3,16}$'
+              description: Username (alphanumeric + `_` or `-`, 3–16 chars)
+              maxLength: 16
+              minLength: 3
+              example: john_doe_43
+            disp_name:
+              type: string
+              description: Display name
+              maxLength: 32
+              example: John Smith
+            user_desc:
+              type: string
+              description: User description / bio
+              maxLength: 512
+              example: Just a curious developer.
+          additionalProperties: false
+          description: Only provided fields are updated. Omitted fields remain unchanged.
+  responses:
+    '200':
+      description: User updated successfully. Returns updated user representation (excluding sensitive fields).
+      content:
+        application/json:
+          schema:
+            $ref: '../schemas/User.yaml'
+    '400':
+      description: Invalid input (e.g., validation failed, nickname/email conflict, malformed JSON)
+    '401':
+      description: Unauthorized — missing or invalid authentication token
+    '403':
+      description: Forbidden — user is not allowed to modify this resource (e.g., not own profile & no admin rights)
+    '404':
+      description: User not found
+    '409':
+      description: Conflict — e.g., requested `nickname` or `mail` already taken by another user
+    '422':
+      description: Unprocessable Entity — semantic errors not caught by schema (e.g., invalid `avatar_id`)
+    '500':
+      description: Unknown server error