Update for ExecutionMode.default

Author: jpsim

CHANGELOG.md

@@ -15,8 +15,8 @@
   This may result in subtle behavioral differences. While performance is significantly improved,
   rules that rely on specific SourceKit behaviors may need adjustment. Users can temporarily
   revert to the legacy SourceKit behavior by setting `default_execution_mode: sourcekit` in
-  their custom rules configuration or `mode: sourcekit` for individual rules. The SourceKit
-  mode is deprecated and will be removed in a future version.  
+  their custom rules configuration or `execution_mode: sourcekit` for individual rules.
+  The SourceKit mode is deprecated and will be removed in a future version.  
   [JP Simard](https://github.com/jpsim)
 
 ### Experimental

Source/SwiftLintFramework/Rules/CustomRules.swift

@@ -106,7 +106,9 @@ struct CustomRules: Rule, CacheDescriptionProvider, ConditionallySourceKitFree {
             let excludingKinds = configuration.excludedMatchKinds
 
             // Determine effective execution mode (defaults to swiftsyntax if not specified)
-            let effectiveMode = configuration.executionMode ?? self.configuration.defaultExecutionMode ?? .swiftsyntax
+            let effectiveMode = configuration.executionMode == .default
+                ? (self.configuration.defaultExecutionMode ?? .swiftsyntax)
+                : configuration.executionMode
             let needsKindMatching = !excludingKinds.isEmpty
 
             let matches: [NSRange]