Admin Sets Instance Message For First Time

sequenceDiagram
    participant adm as Admin
    participant front as Forgejo Frontend
    participant back as Forgejo Backend

    adm ->> front: Navigate to http://forgejo.instance/admin/service_message (GET)
    front ->> back: Call admin.GetServiceMessage with ctx
    back ->> back: Fill ctx with data
    back ->> front: render tplServiceMessage with ctx data
    front ->> adm: Serve Admin Service Message Management Site
    adm ->> front: Enter Text "Lorem Ipsum" in Modal Service Message field
    adm ->> front: Click "Save"
    front ->> front: Convert to form data so backend can extract
    front ->> back: POST form data to {{AppSubUrl}}/admin/service_message?sm_type=modal
    back ->> back: Route request to CreateOrUpdateServiceMessage web endpoint
    back ->> back: Parse Data with binding ServiceMessageForm{}
    back ->> back: Get value for key "sm_type" (modal)
    back ->> back: Create "Service Message" with text and type "modal" in DB
    back ->> front: Redirect to http://forgejo.instance/admin/service_message
    front ->> adm: Show Updated text field holding entered text