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.json

@@ -1,6 +1,6 @@
 {
   "name": "claude-code-workflow",
-  "version": "6.3.14",
+  "version": "6.3.15",
   "description": "JSON-driven multi-agent development framework with intelligent CLI orchestration (Gemini/Qwen/Codex), context-first architecture, and automated workflow execution",
   "type": "module",
   "main": "ccw/src/index.js",