Implement data-categories endpoint #137
Description
Summary
Implement GET /apps/{id}/data-categories endpoint to return categorized groupings of data items for a given app/component. Currently returns 501 Not Implemented.
Proposed solution
Define data categories for ROS 2 or get them from topic namespaces, or allow manifest definition for data categories.
Additional context
- Route already registered in
rest_server.cpp, needs handler implementation - Consider making category mappings configurable via
gateway_params.yamlor manifest.