docs(architecture): RAG retrieval engine architecture set (01-09)

9 docs + index in docs-src/architecture/ documenting the deterministic
retrieval engine: retrieval pipeline, authority rerank, source_class,
source_role, control-intent + diversity, assessment, confidence,
explainability + supersede, framework_* layer. Each doc carries the exact
constants, the rationale behind them, code refs, and the failure class
it addresses. Audit/onboarding reference.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

mkdocs.yml

@@ -56,6 +56,17 @@ markdown_extensions:
 
 nav:
   - Start: index.md
+  - Architektur RAG:
+    - Übersicht: architecture/index.md
+    - 01 Retrieval-Pipeline: architecture/01-retrieval.md
+    - 02 Authority-Re-Ranking: architecture/02-authority.md
+    - 03 source_class: architecture/03-source-class.md
+    - 04 source_role: architecture/04-source-role.md
+    - 05 Control-Intent + Diversity: architecture/05-control-intent.md
+    - 06 Assessment: architecture/06-assessment.md
+    - 07 Confidence: architecture/07-confidence.md
+    - 08 Explainability + Supersede: architecture/08-explainability.md
+    - 09 framework_*-Layer: architecture/09-framework-layer.md
   - Services:
     - AI Compliance SDK:
       - Uebersicht: services/ai-compliance-sdk/index.md