Critical Fixes:
- Fix subagent permission bypass issue where tools executed without prompts
- Restore proper tool execution engine usage in subagent_runner.py
- Remove debug logging and clean up tool execution flow
- Fix test failures in test_subagent_permissions.py

Technical Changes:
- Subagents now properly use original_execute_mcp_tool for permission checks
- Removed "simplified approach" that bypassed tool execution engine
- Restored proper permission flow: subagent → permission manager → main process
- Enhanced tool execution error handling for conversation state protection

Root Cause:
The subagent_runner.py was calling _execute_builtin_tool directly,
completely bypassing the tool_execution_engine.py permission system.
Now uses proper tool execution path with full permission checking.

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

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