refactor: inline node-setup across Node.js actions

Phase 6A: Remove node-setup abstraction layer and inline Node.js setup.

Changes:
- Replace node-setup calls with direct actions/setup-node@v6.0.0
- Inline package manager detection (lockfile-based)
- Add Corepack enablement and package manager installation
- Use Node.js 22 as default version

Actions migrated (5):
- prettier-lint: Inline Node.js setup + package manager detection
- biome-lint: Inline Node.js setup + package manager detection
- eslint-lint: Inline Node.js setup + package manager detection
- pr-lint: Inline Node.js setup (conditional on package.json)
- npm-publish: Inline Node.js setup + package manager detection

Removed:
- node-setup/action.yml (371 lines)
- node-setup/README.md, rules.yml, CustomValidator.py
- _tests/unit/node-setup/validation.spec.sh
- _tests/integration/workflows/node-setup-test.yml
- validate-inputs/tests/test_node-setup_custom.py

Documentation updates:
- CLAUDE.md: Remove node-setup from action list (26 actions)
- generate_listing.cjs: Remove node-setup mappings
- update-validators.py: Remove node-setup custom validator

Result: 26 actions (down from 27), eliminated internal dependency layer.

validate-inputs/scripts/update-validators.py

@@ -311,9 +311,6 @@ class ValidationRuleGenerator:
                 "backoff-strategy": "backoff_strategy",
                 "shell": "shell_type",
             },
-            "node-setup": {
-                "package-manager": "package_manager_enum",
-            },
             "docker-publish": {
                 "registry": "registry_enum",
                 "cache-mode": "cache_mode",

validate-inputs/tests/test_node-setup_custom.py

@@ -1,74 +0,0 @@
-"""Tests for node-setup custom validator.
-
-Generated by generate-tests.py - Do not edit manually.
-"""
-# pylint: disable=invalid-name  # Test file name matches action name
-
-import sys
-from pathlib import Path
-
-# Add action directory to path to import custom validator
-action_path = Path(__file__).parent.parent.parent / "node-setup"
-sys.path.insert(0, str(action_path))
-
-# pylint: disable=wrong-import-position
-from CustomValidator import CustomValidator
-
-
-class TestCustomNodeSetupValidator:
-    """Test cases for node-setup custom validator."""
-
-    def setup_method(self):
-        """Set up test fixtures."""
-        self.validator = CustomValidator("node-setup")
-
-    def teardown_method(self):
-        """Clean up after tests."""
-        self.validator.clear_errors()
-
-    def test_validate_inputs_valid(self):
-        """Test validation with valid inputs."""
-        # TODO: Add specific valid inputs for node-setup
-        inputs = {}
-        result = self.validator.validate_inputs(inputs)
-        # Adjust assertion based on required inputs
-        assert isinstance(result, bool)
-
-    def test_validate_inputs_invalid(self):
-        """Test validation with invalid inputs."""
-        # TODO: Add specific invalid inputs for node-setup
-        inputs = {"invalid_key": "invalid_value"}
-        result = self.validator.validate_inputs(inputs)
-        # Custom validators may have specific validation rules
-        assert isinstance(result, bool)
-
-    def test_required_inputs(self):
-        """Test required inputs detection."""
-        required = self.validator.get_required_inputs()
-        assert isinstance(required, list)
-        # TODO: Assert specific required inputs for node-setup
-
-    def test_validation_rules(self):
-        """Test validation rules."""
-        rules = self.validator.get_validation_rules()
-        assert isinstance(rules, dict)
-        # TODO: Assert specific validation rules for node-setup
-
-    def test_github_expressions(self):
-        """Test GitHub expression handling."""
-        inputs = {
-            "test_input": "${{ github.token }}",
-        }
-        result = self.validator.validate_inputs(inputs)
-        assert isinstance(result, bool)
-        # GitHub expressions should generally be accepted
-
-    def test_error_propagation(self):
-        """Test error propagation from sub-validators."""
-        # Custom validators often use sub-validators
-        # Test that errors are properly propagated
-        inputs = {"test": "value"}
-        self.validator.validate_inputs(inputs)
-        # Check error handling
-        if self.validator.has_errors():
-            assert len(self.validator.errors) > 0