feat(cli): add detailed debug logging for CLI execution

- Add debugLog and errorLog utility functions with DEBUG env control
- Add logging for tool availability check (TOOL_CHECK)
- Add logging for command building (BUILD_CMD)
- Add logging for process spawn (SPAWN, STDIN)
- Add logging for process completion (CLOSE, STATUS)
- Enhance error output with command details, exit code, and stderr
- Add troubleshooting hints for common failures
- Support DEBUG=true or CCW_DEBUG=true environment variables

Closes #46

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

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "claude-code-workflow",
-  "version": "6.3.13",
+  "version": "6.3.15",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "claude-code-workflow",
-      "version": "6.3.13",
+      "version": "6.3.15",
       "license": "MIT",
       "dependencies": {
         "@modelcontextprotocol/sdk": "^1.0.4",