Create "Split Matrix Server" ADRs

Problem:

• The project requirements define the request follow-up communication (Antragsfolgekommunikation) should be transported via Matrix.
• Matrix as a federated communication protocol offers the possibility to separate concerns, e.g. between government and citizens.

Goal:

Define the preferable federation landscape of Matrix servers in the project based on a comparison of different possible alternatives.

ACs:

• follow the architecture decision making process to
  • update solution-architecture!1 in order to decide whether the homeservers for government and citizens should be separated
  • introduce a new sibling ADR to clarify if homeserver operation should be separated (solution-architecture!9)
  • introduce a new sibling ADR to clarify why we do (not) split citizens across different servers/competent authorities across different servers (solution-architecture!11)

Notes/Resources:

• Criterion "Unlinkability" https://gitlab.opencode.de/fitko/matrix-g2x/gitlab-profile/-/blob/main/Leistungsbeschreibung.md?ref_type=heads#254-vermeidung-von-globalen-identifikatoren-zur-unterst%C3%BCtzung-des-schutzziels-der-unlinkability
• Criteria "Principles of Architecture design" https://gitlab.opencode.de/fitko/matrix-g2x/gitlab-profile/-/blob/main/Leistungsbeschreibung.md?ref_type=heads#41-prinzipien-der-architekturgestaltung
• https://gitlab.opencode.de/fitko/matrix-g2x/gitlab-profile/-/blob/main/Leistungsbeschreibung.md?ref_type=heads#25-zielbild:~:text=Architekturvarianten%20konzipiert%20werden%20sollen,%20die%20den%20Betrieb%20mehrere%20Matrix-Server%20vorsehen
• Requirements uIDs: Zapuk_69; Zapuk_91; LB: 2.5.4 (LB_30)