auto-claude: subtask-1-2 - Create GrpcConfig class with development/production configs

Add GrpcConfig class following the pattern from ApiClientConfig with:
- Development config: 192.168.88.228:5011 (plaintext/insecure)
- Production config: grpc-route.goutezplanb.com:443 (TLS)
- Host, port, timeout, useTls, and allowSelfSignedCertificate properties
- Address getter for convenience

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

lib/api/grpc_config.dart

@@ -0,0 +1,59 @@
+/// Configuration for gRPC client connections.
+///
+/// Provides separate configurations for development and production environments
+/// with appropriate security settings for each.
+class GrpcConfig {
+  /// The gRPC server host address.
+  final String host;
+
+  /// The gRPC server port.
+  final int port;
+
+  /// Connection timeout duration.
+  final Duration timeout;
+
+  /// Whether to use TLS for secure connections.
+  ///
+  /// When false, uses insecure (plaintext) credentials suitable only for
+  /// development environments.
+  final bool useTls;
+
+  /// Whether to allow self-signed certificates.
+  ///
+  /// Only applicable when [useTls] is true. Useful for development
+  /// environments with self-signed certificates.
+  final bool allowSelfSignedCertificate;
+
+  const GrpcConfig({
+    required this.host,
+    required this.port,
+    this.timeout = const Duration(seconds: 30),
+    this.useTls = true,
+    this.allowSelfSignedCertificate = false,
+  });
+
+  /// Development configuration pointing to local/development gRPC server.
+  ///
+  /// Uses plaintext (insecure) credentials for development convenience.
+  static const GrpcConfig development = GrpcConfig(
+    host: '192.168.88.228',
+    port: 5011,
+    timeout: Duration(seconds: 30),
+    useTls: false,
+    allowSelfSignedCertificate: true,
+  );
+
+  /// Production configuration for the Plan B Logistics gRPC server.
+  ///
+  /// Uses TLS for secure communication.
+  static const GrpcConfig production = GrpcConfig(
+    host: 'grpc-route.goutezplanb.com',
+    port: 443,
+    timeout: Duration(seconds: 30),
+    useTls: true,
+    allowSelfSignedCertificate: false,
+  );
+
+  /// Returns the full address string in the format "host:port".
+  String get address => '$host:$port';
+}