Add incremental manifest-time code quality checks and JS duplicate method detection

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/RSpade/CodeQuality/Rules/Manifest/ScssClassScope_CodeQualityRule.php

@@ -70,6 +70,14 @@ class ScssClassScope_CodeQualityRule extends CodeQualityRule_Abstract
         return true;
     }
 
+    /**
+     * This is a cross-file rule - needs full manifest context
+     */
+    public function is_incremental(): bool
+    {
+        return false;
+    }
+
     /**
      * Get default severity for this rule
      */