feat: refactor server with shelf_static, return JSON responses, add API docs

bin/routes/auth_routes.dart

@@ -31,7 +31,7 @@ class AuthRoutes {
 
     if (user == null || !BCrypt.checkpw(password, user.pwdHash)) {
       await database.createLog(login, 'Failed login attempt');
-      return Response(401, body: 'Invalid credentials');
+      return Response(401, body: jsonEncode({'error': 'Invalid credentials'}), headers: {'Content-Type': 'application/json'});
     }
 
     // Генерация JWT токена
@@ -44,7 +44,7 @@ class AuthRoutes {
     final token = jwt.sign(SecretKey(secret));
 
     await database.createLog(login, 'Successful login');
-    return Response(200, body: jsonEncode(token));
+    return Response(200, body: jsonEncode({'token': token}), headers: {'Content-Type': 'application/json'});
   }
 
   Future<Response> _register(Request request) async {
@@ -56,7 +56,7 @@ class AuthRoutes {
 
     await database.createUser(login, password);
     await database.createLog(login, 'User registration');
-    return Response(201);
+    return Response(201, body: jsonEncode({'message': 'User registered'}), headers: {'Content-Type': 'application/json'});
   }
 
   Future<Response> _watch(Request request, String login) async {
@@ -64,14 +64,14 @@ class AuthRoutes {
 
     if (!database.isValidShareId(uniqueId!)) {
       await database.createLog(login, 'Accessed invalid share link');
-      return Response(404, body: 'Share link not found');
+      return Response(404, body: jsonEncode({'error': 'Share link not found'}), headers: {'Content-Type': 'application/json'});
     }
 
     final position = await database.getLatestPosition();
 
     if (position == null) {
       await database.createLog(login, 'Accessed share link - no position');
-      return Response(404, body: 'No position available');
+      return Response(404, body: jsonEncode({'error': 'No position available'}), headers: {'Content-Type': 'application/json'});
     }
 
     await database.createLog(login, 'Accessed share link');
@@ -80,6 +80,6 @@ class AuthRoutes {
       'y': position.yValue,
       'last_update': position.lastUpdate,
       'expires_at': position.expiresAt,
-    }));
+    }), headers: {'Content-Type': 'application/json'});
   }
 }