Document node parameters and switch to config-file based launches

[mmmarinho]

Summary

Applies the standard "ROS 2 Nodes & Parameters" README section and converts the launch files to the config-file-based pattern used by sas_robot_driver_ur / sas_robot_driver_kuka.

• Renames launch/sas_robot_driver_ros_composer_example.py → launch/composer_example_launch.py and converts it to load all parameters from config/config.yaml via a config_file launch argument.
• Adds launch/composer_launch.py (single composer node) and launch/watchdog_launch.py (watchdog commander node).
• Adds config/config.yaml with parameter blocks for the three nodes: sas_robot_driver_ros_composer_node, sas_robot_watchdog_commander_node, and the two sas_robot_driver_ros_example instances (named robot_1 and robot_2).
• Adds a ROS 2 Nodes & Parameters README section (and updates AGENTS.md) documenting every parameter of each node (type, mandatory/optional, default, purpose).
• Installs config/ into the package share directory.

Notes

• The composer's robot_driver_client_names entries are topic prefixes of the client nodes; the example launch keeps robot_1/robot_2 as the node names of the two example instances so each reads its own config block.
• This PR is one of a set of companion PRs across the SmartArmStack repositories.

Verification

• python3 -m py_compile passes on all launch files.
• config/config.yaml parses and contains blocks for all node instances; parameter names cross-checked against the node sources.

Note: this PR was created by an AI agent (OpenHands) on behalf of the user.

[mmmarinho]

Is the indentation in the config file correct?

[mmmarinho]

Good question — I re-verified config/config.yaml at the PR head and it is correct:

• Valid YAML: the file parses cleanly with yaml.safe_load.
• Indentation: uniform 2-space indentation throughout (no tabs); the nesting is node_name -> ros__parameters -> <param>, consistent across all four blocks.
• Keys match the effective node names: I cross-checked every top-level key against the node names set by the launch files:
  • robot_1, robot_2 -> set as name='robot_1' / name='robot_2' in composer_example_launch.py
  • robot_composed -> set as name='robot_composed' (also the default of composer_launch.py)
  • sas_robot_watchdog_commander_node -> the watchdog node has no explicit name in watchdog_launch.py, so its effective name is the code name, which the block key matches.

So each node only receives its own block. If you were looking at a specific spot that still seems off, let me know which line and I will adjust it.

This comment was created by an AI agent (OpenHands) on behalf of the user.