fix(.claude/): resolve npm install failure for claude-dir-installer

Fixes issue where npm install -g or ccs update would fail to copy
.claude/ directory to ~/.ccs/.claude/, causing symlink installation
errors. ClaudeDirInstaller now ensures source exists before
ClaudeSymlinkManager attempts linking.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@kaitranntt/ccs",
-  "version": "4.1.0",
+  "version": "4.1.1",
   "description": "Claude Code Switch - Instant profile switching between Claude Sonnet 4.5 and GLM 4.6",
   "keywords": [
     "cli",