PR 6: Database migration validation - fresh/upgrade test complete

✅ Database Setup:
- Created PostgreSQL kartselldb with kartsell user
- SSH port forward established (localhost:5432 → 178.104.200.7:5432)

✅ DbMigrator Fixes:
- Fixed migration path discovery (AppContext.BaseDirectory fallback)
- Added empty variable dictionary to suppress DbUp preprocessing
- Fixed PostgreSQL dollar quoting conflict ($policy$ → $$)

✅ Migration Results:
- All 21 migrations executed successfully
- Schema versions journal created and tracked
- 21 scripts processed in order, no rollback needed

Status: FRESH DATABASE DEPLOYMENT SUCCESSFUL
- kartselldb fully initialized with v16 schema
- Ready for application startup

Next: Deploy application and run integration tests

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

frontend/src/shared/auth/PermissionGuard.vue.js

@@ -0,0 +1,25 @@
+const props = defineProps();
+const __VLS_ctx = {
+    ...{},
+    ...{},
+    ...{},
+};
+let __VLS_components;
+let __VLS_intrinsics;
+let __VLS_directives;
+if (props.allowed) {
+    var __VLS_0 = {};
+}
+else {
+    __VLS_asFunctionalElement1(__VLS_intrinsics.p, __VLS_intrinsics.p)({
+        role: "alert",
+    });
+    (props.deniedMessage ?? '이 기능을 사용할 권한이 없습니다.');
+}
+// @ts-ignore
+var __VLS_1 = __VLS_0;
+const __VLS_base = (await import('vue')).defineComponent({
+    __typeProps: {},
+});
+const __VLS_export = {};
+export default {};