Add linter

Gemfile.lock

@@ -9,6 +9,7 @@ GEM
       base64
     ksuid (1.0.0)
     language_server-protocol (3.17.0.3)
+    lint_roller (1.1.0)
     logger (1.6.0)
     multi_json (1.15.0)
     mustermann (3.0.0)
@@ -54,6 +55,9 @@ GEM
       unicode-display_width (>= 2.4.0, < 3.0)
     rubocop-ast (1.31.3)
       parser (>= 3.3.1.0)
+    rubocop-performance (1.21.1)
+      rubocop (>= 1.48.1, < 2.0)
+      rubocop-ast (>= 1.31.1, < 2.0)
     ruby-lsp (0.17.3)
       language_server-protocol (~> 3.17.0)
       prism (>= 0.29.0, < 0.31)
@@ -74,6 +78,18 @@ GEM
       sinatra (= 4.0.0)
       tilt (~> 2.0)
     sorbet-runtime (0.5.11435)
+    standard (1.39.1)
+      language_server-protocol (~> 3.17.0.2)
+      lint_roller (~> 1.0)
+      rubocop (~> 1.64.0)
+      standard-custom (~> 1.0.0)
+      standard-performance (~> 1.4)
+    standard-custom (1.0.2)
+      lint_roller (~> 1.0)
+      rubocop (~> 1.50)
+    standard-performance (1.4.0)
+      lint_roller (~> 1.1)
+      rubocop-performance (~> 1.21.0)
     strscan (3.1.0)
     test-unit (3.6.2)
       power_assert
@@ -102,6 +118,7 @@ DEPENDENCIES
   ruby-lsp
   sinatra
   sinatra-contrib
+  standard
   test-unit
   ulid
   uuid7