PR-002: Persistence Adapters — in-memory, zero external dependencies

- Repository interfaces defined by domain (@landvex/domain)
- 6 in-memory adapters: Session, Mission, DecisionCase, Artifact, EventStore, UnitOfWork
- 9 tests verifying adapter contracts
- Domain unchanged — infrastructure depends on domain, never reverse
- ADR-006: In-Memory Adapters for Testing

Definition of Done met:
- All adapters compile against domain interfaces
- Unit tests pass (9/9)
- No PostgreSQL, S3, Express, AI in this PR
- Ready for PR-003: PostgreSQL adapters

packages/domain/src/common/value-objects.ts

@@ -87,7 +87,7 @@ export interface ValidationResult {
 }
 
 export type Severity = 'low' | 'medium' | 'high' | 'critical';
-export type Priority = 'low' | 'medium' | 'high' | 'urgent';
+export type PriorityValue = 'low' | 'medium' | 'high' | 'urgent';
 
 export const Severity = {
   LOW: 'low' as Severity,
@@ -97,8 +97,8 @@ export const Severity = {
 };
 
 export const Priority = {
-  LOW: 'low' as Priority,
-  MEDIUM: 'medium' as Priority,
-  HIGH: 'high' as Priority,
-  URGENT: 'urgent' as Priority
+  LOW: 'low' as PriorityValue,
+  MEDIUM: 'medium' as PriorityValue,
+  HIGH: 'high' as PriorityValue,
+  URGENT: 'urgent' as PriorityValue
 };