Implement unified OGP agent with platform detection and conditional logic

Co-authored-by: iaretechnician <2749183+iaretechnician@users.noreply.github.com>

AGENT_UNIFICATION.md

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+# OGP Agent Unification
+
+## Overview
+This project unifies the Linux and Windows OGP (Open Game Panel) agent files into a single cross-platform agent that works on both Linux and Windows/Cygwin systems.
+
+## Key Platform-Specific Differences Addressed
+
+### 1. SteamCMD Binary Paths
+- **Linux**: Uses `steamcmd.sh`
+- **Windows**: Uses `steamcmd.exe`
+- **Solution**: Platform-conditional constant `STEAMCMD_CLIENT_BIN`
+
+### 2. Sudo Functionality
+- **Linux**: Full sudo support with password-based authentication
+- **Windows**: No sudo functionality (different permission model)
+- **Solution**: Conditional sudo functions that are no-ops on Windows
+
+### 3. User Management
+- **Linux**: Uses `LINUX_USER_PER_GAME_SERVER` and `SERVER_RUNNER_USER`
+- **Windows**: Uses `USER_RUNNING_SCRIPT` with Cygwin-specific fallbacks
+- **Solution**: Platform-conditional user constants
+
+### 4. Log Rotation
+- **Linux**: Automated log rotation functionality
+- **Windows**: Static log handling
+- **Solution**: Conditional log rotation code block
+
+### 5. Screen Configuration
+- **Linux**: Dynamic screenrc file modification with temporary files
+- **Windows**: Static screenrc usage with basic screen session cleanup
+- **Solution**: Conditional screen configuration logic
+
+### 6. File Permissions
+- **Linux**: Complex permission management using chmod, setfacl, chattr
+- **Windows**: Simpler permission model
+- **Solution**: Linux-only permission functions
+
+### 7. Process Execution
+- **Linux**: Bash scripts with respawn logic and Wine environment variables
+- **Windows**: Batch files with priority/affinity control and Cygwin path conversion
+- **Solution**: Platform-specific `create_screen_cmd` and `create_screen_cmd_loop` functions
+
+### 8. Path Handling
+- **Linux**: Standard Unix paths
+- **Windows**: Cygwin path conversion using `cygpath -wa`
+- **Solution**: Platform-specific path handling in `replace_OGP_Env_Vars`
+
+## Implementation Strategy
+
+The unified agent uses:
+1. **Platform Detection**: `$^O` variable to detect Windows/Cygwin vs Linux
+2. **Conditional Constants**: Platform-specific values set at compile time
+3. **Conditional Logic**: Runtime platform checks for different behaviors
+4. **Function Overloading**: Same function names with platform-specific implementations
+
+## Files
+
+- `ogp_agent_unified.pl`: The unified agent file
+- `AGENT_UNIFICATION.md`: This documentation
+- `_agent-linux/`: Original Linux agent (preserved)
+- `_agent-windows/`: Original Windows agent (preserved)
+
+## Testing
+
+The unified agent can be tested on both platforms:
+- Linux: Standard Perl environment
+- Windows: Cygwin with Perl environment
+
+## Deployment
+
+To use the unified agent:
+1. Copy `ogp_agent_unified.pl` to the target system
+2. Ensure all required Perl modules are installed
+3. Run with same command-line options as original agents
+4. The agent will automatically detect the platform and behave appropriately
+
+## Benefits
+
+1. **Single Codebase**: Easier maintenance and updates
+2. **Reduced Duplication**: No need to maintain two separate files
+3. **Consistent Features**: New features automatically work on both platforms
+4. **Simplified Deployment**: One file works everywhere