Improved NVIDIA support out-of-the-box and other fixes

[ppswaroopa]

This PR introduces improved support for NVIDIA graphics cards out-of-the-box and fixes inconsistencies and other issues as listed in the CHANGELOG. Closes #4

This PR also moves the version to v1.2.0

Added

• Modern NVIDIA Container Support: Support for runtime: nvidia in generated docker-compose.yml and the __GLX_VENDOR_LIBRARY_NAME=nvidia environment variable to ensure correct GPU offloading and OpenGL vendor selection.
• Enhanced Hybrid GPU Support: Native support for Intel/NVIDIA hybrid laptops via mandatory /dev/dri volume mounts for Linux hosts and explicit installation of libgl1, libglvnd-dev, and libegl1 for vendor-neutral GL dispatch.
• Intelligent Choice Relationships: Variant selections like desktop-full now automatically imply required packages (rviz2, gazebo/gz_sim), and GUI packages automatically enable x11 display forwarding.
• Core Engine Upgrades: New resolve_config() method in both Python and JS core modules to handle automatic dependency resolution and OS-specific scaffolding.
• Output-shape regression tests in tests/test_output_shape.py to verify repo-root workspace mounts, shell config generation, NVIDIA compose behavior, and README/package consistency.
• Web bundle regression tests in tests/test_web_bundle.py to verify the website zip export contains the expected files and preserves byte-identical generated content.
• Readiness checks in CI/validate.sh for writable default workspaces, colcon mixin list, and Oh My Zsh ownership in generated non-root containers.
• CI workflow coverage for the new readiness invariants, including mounted default workspace validation and source-change triggers for heavier generator test jobs.
• A lightweight zip bundler for the web UI and a local scripts/run_act.sh helper for reproducible sequential act runs without introducing third-party JS dependencies.

Changed

• Modernized GPU acceleration logic in docker-compose.yml to prefer the runtime: nvidia directive over the legacy deploy: resources block for broader compatibility outside of Swarm.
• Updated generated README with specific troubleshooting guidance and caveats for users on hybrid GPU laptop hardware (e.g., prime-select nvidia hints).
• Generated docker-compose.yml now mounts the current directory into the configured ROS workspace by default instead of creating a nested ./ros2_ws bind mount.
• Generated Dockerfiles now install Oh My Zsh in the selected user's home after switching to that user, while keeping Zsh as a normal optional tool selection.
• Generated shell bootstrap now writes ROS/environment setup into .bashrc when bashrc is selected and into .zshrc when zsh is selected.
• The CLI wizard now preselects propagated package and tool defaults for presets such as desktop-full, matching the web UI instead of only applying those implications at final generation time.
• Generated README content now reflects the repo-root workspace workflow, includes clearer NVIDIA host/runtime guidance, and documents the new local act runner behavior.
• CLI/web generation and CI helpers now consistently use the standard non-root user mode and current host UID mapping for dev-container readiness.
• Shared defaults now drive Web, CLI, and CI generation consistently, including the default ros2-<distro> container name and default tool selection set.
• TensorRT now behaves like a real selectable package and emits install steps from the NVIDIA CUDA image package repositories instead of acting as a placeholder selection.
• The web UI now exports a real zip bundle containing Dockerfile, docker-compose.yml, and README.md, and local act runs now execute jobs sequentially with matrix fan-out capped to keep disk usage manageable.

Fixed

• Resolved generated non-root dev environments depending on Docker auto-creating a writable workspace directory with the correct ownership.
• Resolved generated Zsh environments installing Oh My Zsh under /root instead of the selected non-root user.
• Removed misleading generated SSH port documentation when host networking is enabled and Docker would discard published ports.
• Resolved website download bundles requiring manual renaming of Dockerfile before the generated compose setup could build.
• Resolved generated Gazebo environments missing the ROS plugin library path, which could prevent Gazebo from launching until GAZEBO_PLUGIN_PATH was exported manually.

[ppswaroopa]

OK