fix: Add Windows platform detection to bash tool

[kevinkre]

Problem

The cipher bash tool had hardcoded /bin/bash paths that don't exist on Windows, causing ENOENT (Error: No Entry) failures when running as MCP server on Windows.

Root Cause

The bash tool was using Unix-specific absolute paths without checking the operating system. Windows has cmd.exe and powershell.exe, but no /bin/bash directory.

Solution

Added OS detection using the platform module to select the appropriate shell:

• Windows: Uses cmd.exe with args ['/c']
• Unix/Linux/Mac: Uses /bin/bash with args ['-c']

Changes Made

Modified: src/core/brain/tools/definitions/system/bash.ts

1. Imported platform from the os module
2. Created getShellCommand() helper function that returns:
   • Windows: { shell: 'cmd.exe', args: ['/c'] }
   • Unix: { shell: '/bin/bash', args: ['-c'] }
3. Updated two execution points:
   • BashSession.initialize() - Uses platform-appropriate shell
   • executeBashCommand() - Uses platform-appropriate shell

Testing

• ✅ Builds successfully on Windows
• ✅ Works with PowerShell and CMD
• ✅ Backwards compatible with Unix systems
• ✅ No breaking changes to existing Unix behavior

Scope

This is a minimal, surgical fix that:

• Only affects the bash tool
• Maintains backwards compatibility
• Solves Windows compatibility without affecting other tools
• Enables Windows users (like Claude Desktop users) to use cipher MCP server