feat: API auth with custom headers

lib/core/services/input_validation_service.dart

@@ -27,10 +27,10 @@ class InputValidationService {
     return null;
   }
 
-  /// Validate URL
+  /// Validate URL (enhanced version for server addresses)
   static String? validateUrl(String? value, {bool required = true}) {
     if (value == null || value.isEmpty) {
-      return required ? 'URL is required' : null;
+      return required ? 'Server address is required' : null;
     }
 
     final trimmed = value.trim();
@@ -38,21 +38,58 @@ class InputValidationService {
     // Add protocol if missing
     String urlToValidate = trimmed;
     if (!trimmed.startsWith('http://') && !trimmed.startsWith('https://')) {
-      urlToValidate = 'https://$trimmed';
+      urlToValidate = 'http://$trimmed';
     }
 
     try {
       final uri = Uri.parse(urlToValidate);
-      if (!uri.hasScheme || !uri.hasAuthority) {
-        return 'Please enter a valid URL';
+      
+      // Validate scheme
+      if (!uri.hasScheme || (uri.scheme != 'http' && uri.scheme != 'https')) {
+        return 'Use http:// or https:// only';
       }
+      
+      // Validate host
+      if (!uri.hasAuthority || uri.host.isEmpty) {
+        return 'Please enter a server address (e.g., 192.168.1.10:3000)';
+      }
+
+      // Validate port if specified
+      if (uri.hasPort) {
+        if (uri.port < 1 || uri.port > 65535) {
+          return 'Port must be between 1 and 65535';
+        }
+      }
+
+      // Validate IP address format if it looks like an IP
+      if (_isIPAddress(uri.host) && !_isValidIPAddress(uri.host)) {
+        return 'Invalid IP address format (use 192.168.1.10)';
+      }
+
     } catch (e) {
-      return 'Please enter a valid URL';
+      return 'Invalid server address format';
     }
 
     return null;
   }
 
+  /// Check if a string looks like an IP address
+  static bool _isIPAddress(String host) {
+    return RegExp(r'^\d+\.\d+\.\d+\.\d+$').hasMatch(host);
+  }
+
+  /// Validate IP address format
+  static bool _isValidIPAddress(String ip) {
+    final parts = ip.split('.');
+    if (parts.length != 4) return false;
+    
+    for (final part in parts) {
+      final num = int.tryParse(part);
+      if (num == null || num < 0 || num > 255) return false;
+    }
+    return true;
+  }
+
   /// Validate password strength
   static String? validatePassword(String? value, {bool checkStrength = true}) {
     if (value == null || value.isEmpty) {