feat: implement notifications and admin notification api

docs/resources/admin_notification.md

@@ -0,0 +1,36 @@
+---
+# generated by https://github.com/hashicorp/terraform-plugin-docs
+page_title: "immich_admin_notification Resource - immich"
+subcategory: ""
+description: |-
+  Sends a system-wide notification as an administrator. Note: This resource triggers a notification upon creation. Deleting the resource will attempt to remove the notification.
+---
+
+# immich_admin_notification (Resource)
+
+Sends a system-wide notification as an administrator. Note: This resource triggers a notification upon creation. Deleting the resource will attempt to remove the notification.
+
+## Example Usage
+
+```terraform
+resource "immich_admin_notification" "announcement" {
+  type        = "SYSTEM"
+  level       = "INFO"
+  title       = "Maintenance Scheduled"
+  description = "Immich will be down for maintenance on Sunday at 2 AM UTC."
+}
+```
+
+<!-- schema generated by tfplugindocs -->
+## Schema
+
+### Required
+
+- `description` (String) Notification message body.
+- `level` (String) Severity level (`INFO`, `WARNING`, `ERROR`).
+- `title` (String) Notification title.
+- `type` (String) Type of notification (e.g. `SYSTEM`).
+
+### Read-Only
+
+- `id` (String) Unique identifier for the created notification.