refactor(platform): address code review feedback for node-finder

- Extract VERSION_DIR_PATTERN regex to named constant
- Pass logger to findNodeViaShell for consistent debug logging
- Fix buildEnhancedPath to not add trailing delimiter for empty currentPath

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

libs/platform/tests/node-finder.test.ts

@@ -87,12 +87,12 @@ describe('node-finder', () => {
       expect(result).toBe(currentPath);
     });
 
-    it('should handle empty currentPath', () => {
+    it('should handle empty currentPath without trailing delimiter', () => {
       const nodePath = '/opt/homebrew/bin/node';
 
       const result = buildEnhancedPath(nodePath, '');
 
-      expect(result).toBe(`/opt/homebrew/bin${delimiter}`);
+      expect(result).toBe('/opt/homebrew/bin');
     });
 
     it('should handle Windows-style paths', () => {
@@ -118,7 +118,7 @@ describe('node-finder', () => {
 
       const result = buildEnhancedPath(nodePath);
 
-      expect(result).toBe(`/usr/local/bin${delimiter}`);
+      expect(result).toBe('/usr/local/bin');
     });
   });
 });