feat(course-package): add publish/unpublish with snapshot locking

- Add published_snapshot (jsonb) and published_at (timestamp) columns
- New POST publish/{id} endpoint: stores snapshot JSON, locks editing
- New POST unpublish/{id} endpoint: clears published_at for editing
- Block update and sync_items when published_at is set
- Frontend detail page with conditional edit/publish/unpublish buttons

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

htykc_models/migrations/2026-04-30-124521_add_published_snapshot_to_course_package/down.sql

@@ -0,0 +1,2 @@
+ALTER TABLE course_package DROP COLUMN IF EXISTS published_snapshot;
+ALTER TABLE course_package DROP COLUMN IF EXISTS published_at;

htykc_models/migrations/2026-04-30-124521_add_published_snapshot_to_course_package/up.sql

@@ -0,0 +1,2 @@
+ALTER TABLE course_package ADD COLUMN published_snapshot jsonb;
+ALTER TABLE course_package ADD COLUMN published_at timestamp;

htykc_models/src/models.rs

@@ -747,6 +747,8 @@ pub struct CoursePackage {
     pub updated_at: Option<NaiveDateTime>,
     pub is_delete: Option<bool>,
     pub org_id: Option<String>,
+    pub published_snapshot: Option<serde_json::Value>,
+    pub published_at: Option<NaiveDateTime>,
 }
 
 #[derive(Serialize, Deserialize, Debug, Clone)]
@@ -767,6 +769,8 @@ pub struct ReqCoursePackage {
     pub updated_at: Option<NaiveDateTime>,
     pub is_delete: Option<bool>,
     pub org_id: Option<String>,
+    pub published_snapshot: Option<serde_json::Value>,
+    pub published_at: Option<NaiveDateTime>,
 }
 
 impl CoursePackage {

htykc_models/src/schema.rs

@@ -113,6 +113,8 @@ diesel::table! {
         updated_at -> Nullable<Timestamp>,
         is_delete -> Nullable<Bool>,
         org_id -> Nullable<Varchar>,
+        published_snapshot -> Nullable<Jsonb>,
+        published_at -> Nullable<Timestamp>,
     }
 }