refactor: Migrate from monolithic to modular architecture

1. **Dokumentation der Architektur:**
    - Vervollständigen Sie die C4-Diagramme im docs-Verzeichnis
    - Dokumentieren Sie die wichtigsten Architekturentscheidungen in ADRs

2. **Redis-Integration finalisieren:**
    - Implementieren Sie die verteilte Cache-Lösung für die Offline-Fähigkeit
    - Nutzen Sie Redis Streams für das Event-Sourcing

docs/architecture/adr/0000-adr-template.md

@@ -0,0 +1,27 @@
+# ADR-0000: Architecture Decision Record Template
+
+## Status
+
+[Proposed | Accepted | Deprecated | Superseded]
+
+If superseded, include a reference to the new ADR: [ADR-XXXX](XXXX-filename.md)
+
+## Context
+
+Describe the context and problem statement, e.g., in free form using two to three sentences. You may want to articulate the problem in form of a question.
+
+## Decision
+
+Describe the decision that was made.
+
+## Consequences
+
+Describe the resulting context after applying the decision. All consequences should be listed here, not just the "positive" ones. A particular decision may have positive, negative, and neutral consequences, but all of them affect the team and project in the future.
+
+## Alternatives Considered
+
+What other options were considered, and why were they not chosen?
+
+## References
+
+- [Link to relevant documentation, discussions, etc.]