Support substitution for fault manager yaml file

[nnarain]

Pull Request

Summary

Allow launch substitution for fault manager parameter file.

For example I want to do this:

fault_manager:
  ros__parameters:
    database_path: /tmp/ros2_medkit/faults.db
    healing_enabled: true
    correlation.config_file: $(find-pkg-share my_robot)/config/fault_correlation.yaml

otherwise the correlation config file was read as $(find-pkg-share my_robot)/config/fault_correlation.yaml by the fault manager.

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Issue

Link the related issue (required):

• Resolves Allow substitutions in fault manager parameter file #633

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Type

• Bug fix
• New feature or tests
• Breaking change
• Documentation only

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Testing

local testing

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Checklist

• Breaking changes are clearly described (and announced in docs / changelog if needed)
• Tests were added or updated if needed
• Docs were updated if behavior or public API changed

[Copilot]

Pull request overview

This PR updates the ros2_medkit_fault_manager launch setup to support ROS 2 launch substitutions inside the fault manager YAML parameter file (e.g., $(find-pkg-share my_robot)), so parameter values like correlation.config_file resolve to real paths at launch-time instead of being passed through as raw strings.

Changes:

• Switch fault_manager.launch.py to load the parameter YAML via launch_ros.descriptions.ParameterFile(..., allow_substs=True) so substitutions are expanded.
• Add an informational log line when the fault manager loads the correlation config file to improve observability during startup.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/ros2_medkit_fault_manager/src/fault_manager_node.cpp	Adds a startup log indicating which correlation config file path is being loaded.
src/ros2_medkit_fault_manager/launch/fault_manager.launch.py	Uses ParameterFile(..., allow_substs=True) to enable launch substitutions within the YAML parameter file.

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