fix: node-setup caching, validate-inputs optional_inputs type (#320)

* fix: node-setup caching, validate-inputs optional_inputs type

* test(validate-inputs): dict optional_inputs backward compatibility

Verify that legacy dict format for optional_inputs correctly generates
conventions from dict keys. Updates existing test to expect list type
for optional_inputs default.

node-setup/action.yml

@@ -275,7 +275,8 @@ runs:
       with:
         node-version: ${{ steps.version.outputs.detected-version }}
         registry-url: ${{ inputs.registry-url }}
-        cache: false
+        # Note: cache parameter removed for actions/setup-node@v6 compatibility
+        # Caching is handled separately via common-cache action (step: Cache Dependencies)
 
     - name: Enable Corepack
       id: corepack