[MAINTENANCE] Automate Carla libcarla dependencies management in build system

[yunlishao]

Task Summary
Automate the management of Carla dependencies by integrating the copy and rename operation of ${CARLA_Root}\PythonAPI\carla\dependencies\ to ${FIXS_Root}\CommonLib\libcarla\ into the build system.

Why is this needed?
Currently, per doc/CARLAdoc.md:35, users must manually copy the Carla dependencies directory after building LibCarla:

Once the build is finished, copy the directory ${CARLA_Root}\PythonAPI\carla\dependencies\ into the ${FIXS_Root}\CommonLib\ and rename the directory as libcarla.

This manual step is error-prone and breaks the automated build workflow established by the dispatch system. Automating this will:

• Ensure consistent Carla dependency management across development environments
• Reduce setup friction for new developers
• Align with existing build automation patterns (yaml-cpp, libevent, CarMaker, dSPACE)
• Prevent build failures due to missing or incorrectly placed libcarla dependencies

Scope of Work
The automation should integrate into the existing modular build system:

1. Configuration: Add Carla path detection to dependencies.yaml (similar to existing tool entries)

   • carla_root: Path to Carla installation
   • carla_version: Version tracking (e.g., "0.9.15")

2. Detection Script: Extend scripts/dispatch/detect_tool_paths.ps1 to locate Carla installation

   • Search common installation paths: C:\CARLA, C:\Program Files\CARLA, user-specified paths
   • Validate PythonAPI\carla\dependencies\ exists
   • Return Carla root path and version

3. Build Script: Create new dispatch script scripts\dispatch\6_carla_dependencies.ps1

   • Check if ${CARLA_Root}\PythonAPI\carla\dependencies\ exists
   • Copy directory to ${FIXS_Root}\CommonLib\libcarla\
   • Handle existing libcarla directory (backup/overwrite with user confirmation in manual mode)
   • Log operation to build.log and build_summary.log
   • Skip gracefully if Carla not detected (not all developers need Carla)

4. Integration: Update dispatch.bat to call the new script after external libraries step

   • Execute after 1_external_libraries.bat (libcarla is an external dependency)
   • Before 2_core_components.bat (VirtualEnvironment.lib depends on libcarla headers)

5. Documentation: Update doc/BUILD.md and doc/CARLAdoc.md

   • Document automated Carla dependency management
   • Explain how to configure Carla path in dependencies.yaml
   • Note manual fallback if auto-detection fails

Environment (if version-specific)

• CARLA version: 0.9.15 (current target version per doc/CARLAdoc.md)
• Visual Studio: 2022 17.8 (MSVC 14.3, per Carla build requirements)
• Build system: PowerShell-based dispatch scripts (Windows-only)

Risks or Dependencies

• Carla installation variability: Unlike MATLAB/dSPACE which have standard install paths, Carla may be in custom locations

  • Mitigation: Support both auto-detection and manual path specification in dependencies.yaml

• Breaking existing workflows: Some users may have manually managed libcarla with custom modifications

  • Mitigation: Add backup/confirmation logic; document migration path

• Cross-version compatibility: Future Carla versions may change dependency structure

  • Mitigation: Version-specific handling in detection script; clear error messages

• Dependency ordering: VirtualEnvironment.lib compilation requires libcarla headers to be in place first

  • Must execute before step 2 (core components) in dispatch sequence

Additional Context
Related documentation:

• doc/CARLAdoc.md:35 - Current manual process
• doc/BUILD.md - Build system architecture
• dependencies.yaml - Central configuration for tool versions
• scripts/dispatch/detect_tool_paths.ps1 - Tool detection patterns

Example existing automation pattern (dSPACE libraries):

• Detection in detect_tool_paths.ps1 finds dSPACE installation
• Build script 4b_carmaker_dspace.ps1 compiles version-specific libraries
• Output copied to CommonLib/ and build/ directories
• Logged to build summary files

The Carla automation should follow this established pattern for consistency.