Tighten RuboCop targets

Explicitly include Ruby sources/Gemfile/Rakefile, silence extension
auto-suggestions, and exclude tmp artifacts for cleaner lint scope.

Author: evolve75

.rubocop.yml

@@ -9,10 +9,16 @@ plugins:
 
 AllCops:
   NewCops: enable
+  SuggestExtensions: false
   TargetRubyVersion: 3.1
+  Include:
+    - 'Gemfile'
+    - 'Rakefile'
+    - '**/*.rb'
   Exclude:
     - 'pkg/**/*'
     - 'vendor/**/*'
+    - 'tmp/**/*'
 
 Lint/UselessAssignment:
   Exclude: