feat: Implement versioning documentation

docs/versioning/ARCHITECTURE.md

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+# Versioning System Architecture
+
+**System design, data flow, and architectural decisions**
+
+## System Overview
+
+The Universal Versioning System is a relational database-backed solution for tracking all changes to entities throughout their lifecycle. It uses PostgreSQL triggers, session variables, and type-safe relational tables to provide automatic, transparent versioning.
+
+## Design Philosophy
+
+### Core Principles
+
+1. **Automatic & Transparent** - Versioning happens automatically via triggers
+2. **Pure Relational** - No JSONB storage, all fields are typed columns
+3. **Audit-First** - Every change is attributed to a user and optionally a submission
+4. **Type-Safe** - Foreign keys and constraints enforce data integrity
+5. **Performance-Conscious** - Proper indexing and cleanup mechanisms
+
+### Why Not JSONB?
+
+The previous system stored versions as JSONB blobs. We migrated to relational for:
+
+| Issue with JSONB | Relational Solution |
+|------------------|---------------------|
+| Not queryable without JSONB operators | Standard SQL WHERE clauses |
+| No type safety | Column-level types and constraints |
+| Poor performance on large datasets | Indexed columns |
+| Can't use foreign keys | Full referential integrity |
+| Complex RLS policies | Standard column-level RLS |
+
+## High-Level Architecture
+
+```mermaid
+graph TB
+    subgraph "Frontend Layer"
+        UI[React Components]
+        HOOKS[React Hooks]
+    end
+    
+    subgraph "Backend Layer"
+        EDGE[Edge Functions]
+        DB[(PostgreSQL)]
+        TRIGGERS[Database Triggers]
+    end
+    
+    UI --> HOOKS
+    HOOKS --> DB
+    EDGE --> SESSION[Set Session Variables]
+    SESSION --> DB
+    DB --> TRIGGERS
+    TRIGGERS --> VERSIONS[Version Tables]
+    
+    style VERSIONS fill:#4CAF50
+    style TRIGGERS fill:#2196F3
+    style SESSION fill:#FF9800