Tambah panduan setup lokal untuk troubleshooting Failed to fetch

SETUP_LOCAL.md

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+# Setup Lokal Development (Laragon/XAMPP)
+
+## Masalah: "Failed to fetch" di Localhost
+
+Jika Anda mendapat error "Failed to fetch" saat mengakses:
+```
+http://localhost/retribusi_bapenda/retribusi%20(frontend)/public/index.html
+```
+
+## Solusi
+
+### Opsi 1: Akses Langsung ke Public Folder (Recommended)
+
+Karena document root seharusnya di folder `public/`, akses langsung ke:
+
+```
+http://localhost/retribusi_bapenda/retribusi%20(frontend)/public/index.html
+```
+
+Atau jika folder `public/` sudah di-set sebagai document root:
+
+```
+http://localhost/index.html
+```
+
+### Opsi 2: Setup Virtual Host di Laragon
+
+1. Buka Laragon
+2. Klik kanan pada folder project → **Add Virtual Host**
+3. Set document root ke: `C:\laragon\www\RETRIBUSI_BAPENDA\retribusi (frontend)\public`
+4. Set domain: `retribusi.local` (atau sesuai keinginan)
+5. Restart Laragon
+6. Akses: `http://retribusi.local/index.html`
+
+### Opsi 3: Gunakan PHP Built-in Server
+
+```bash
+cd "C:\laragon\www\RETRIBUSI_BAPENDA\retribusi (frontend)\public"
+php -S localhost:8080
+```
+
+Akses: `http://localhost:8080/index.html`
+
+## Konfigurasi API
+
+Pastikan file `public/dashboard/js/config.js` sudah benar untuk lokal:
+
+```javascript
+// Untuk Laragon/Apache (path-based)
+return 'http://localhost/api-btekno/public';
+
+// ATAU untuk PHP built-in server
+return 'http://localhost:8000';
+```
+
+## Troubleshooting
+
+### Error: "Failed to fetch"
+
+1. **Cek path file**: Pastikan file `public/index.html` ada
+2. **Cek document root**: Pastikan server mengarah ke folder `public/`
+3. **Cek CORS**: Pastikan backend API sudah allow origin `http://localhost`
+4. **Cek browser console**: Lihat error detail di Developer Tools (F12)
+
+### Error: "Module not found"
+
+1. Pastikan menggunakan ES6 modules (`type="module"` di script tag)
+2. Pastikan path import benar (relative path dari file HTML)
+3. Pastikan file JavaScript ada di lokasi yang benar
+
+### Error: "CORS policy"
+
+1. Pastikan backend API sudah setup CORS untuk `http://localhost`
+2. Cek file `api/cors_handler.php` atau `api/cors-handler.php`
+3. Pastikan header `Access-Control-Allow-Origin` sudah di-set
+
+## Struktur Path yang Benar
+
+```
+retribusi (frontend)/
+└── public/                    ← Document root
+    ├── index.html            ← Login page
+    └── dashboard/
+        ├── dashboard.html
+        ├── event.html
+        └── js/
+            ├── config.js
+            ├── api.js
+            └── auth.js
+```
+
+## Quick Test
+
+1. Buka browser
+2. Akses: `http://localhost/retribusi_bapenda/retribusi%20(frontend)/public/index.html`
+3. Atau setup virtual host dan akses: `http://retribusi.local/index.html`
+4. Cek browser console (F12) untuk error detail
+