Get Platform DFA to valid state

Platform DFA is defined in https://eclipse-score.github.io/process_description/main/process_areas/safety_analysis/safety_analysis_workflow.html#wf__analyse_platform_featarch
Draft exists in https://eclipse-score.github.io/score/main/safety/platform_dfa.html - this document has to be filled out, but not formally reviewed - this is part of another sub-task.
As this DFA is on the highest level, even a modification of the checklist for this task may be needed, as different aspects may be in focus at this level.

As a precondition to perform the analysis, a platform architecture has to be documented.
Currently available is https://eclipse-score.github.io/score/main/handbook/project_basics/software_architecture_overview.html - which does not show relations of the modules.
For this https://github.com/eclipse-score/score/pull/2346#discussion_r2815810940 should be considered.

plat_saf_dfa exists in metamodel https://github.com/eclipse-score/docs-as-code/blob/main/src/extensions/score_metamodel/metamodel.yaml (currently links to feature architecture), but not the SW platform architecture sphinx need.