Fix database constraint error in template seeding

- Replace insert() with upsert() to handle existing templates
- Add onConflict: 'key' to update duplicates instead of failing
- This resolves "duplicate key value violates unique constraint" error
- Templates will now be properly updated/seeded on first visit

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/components/admin/settings/NotifikasiTab.tsx

@@ -422,7 +422,7 @@ export function NotifikasiTab() {
   const seedTemplates = async () => {
     try {
       console.log('Seeding default templates...');
-      const toInsert = DEFAULT_TEMPLATES.map(t => ({
+      const toUpsert = DEFAULT_TEMPLATES.map(t => ({
         key: t.key,
         name: t.name,
         is_active: false,
@@ -431,8 +431,14 @@ export function NotifikasiTab() {
         webhook_url: '',
       }));
 
-      console.log('Inserting templates:', toInsert.length);
+      console.log('Upserting templates:', toUpsert.length);
-      const { data, error } = await supabase.from('notification_templates').insert(toInsert).select();
+      const { data, error } = await supabase
+        .from('notification_templates')
+        .upsert(toUpsert, {
+          onConflict: 'key',
+          ignoreDuplicates: false
+        })
+        .select();
 
       if (error) {
         console.error('Error seeding templates:', error);
@@ -444,7 +450,7 @@ export function NotifikasiTab() {
         return;
       }
 
-      console.log('Templates seeded successfully:', data);
+      console.log('Templates seeded/updated successfully:', data);
       if (data) {
         setTemplates(data);
         toast({