Add command files and enhance session management features

backend/bin/server.dart

@@ -0,0 +1,48 @@
+import 'dart:io';
+
+import 'package:http/http.dart' as http;
+import 'package:shelf/shelf.dart';
+import 'package:shelf/shelf_io.dart' as shelf_io;
+import 'package:shelf_router/shelf_router.dart';
+
+Future<void> main(List<String> args) async {
+  final apiKey = Platform.environment['OPENROUTER_API_KEY'];
+  final baseUrl = Platform.environment['OPENROUTER_BASE_URL'] ?? 'https://openrouter.ai/api/v1';
+
+  final router = Router()
+    ..post('/v1/chat/completions', (Request request) async {
+      if (apiKey == null || apiKey.isEmpty) {
+        return Response(500, body: 'OPENROUTER_API_KEY is not set');
+      }
+
+      final body = await request.readAsString();
+      final upstream = await http.post(
+        Uri.parse('$baseUrl/chat/completions'),
+        headers: {
+          'Authorization': 'Bearer $apiKey',
+          'Content-Type': 'application/json',
+          'Accept': 'application/json',
+          'HTTP-Referer': 'http://localhost:8080',
+          'X-Title': 'clawd_code backend',
+        },
+        body: body,
+      );
+
+      return Response(
+        upstream.statusCode,
+        body: upstream.body,
+        headers: {
+          'content-type': upstream.headers['content-type'] ?? 'application/json',
+        },
+      );
+    })
+    ..post('/v1/models', (Request request) => Response(405, body: 'Method not allowed'))
+    ..all('/<ignored|.*>', (Request request, String ignored) => Response.notFound('Not found'));
+
+  final handler = Pipeline()
+      .addMiddleware(logRequests())
+      .addHandler(router.call);
+
+  final server = await shelf_io.serve(handler, InternetAddress.anyIPv4, 8080);
+  stdout.writeln('Serving at http://${server.address.host}:${server.port}');
+}