docs: Align documentation with true microservices architecture

Transform all documentation from modular monolith to true microservices
architecture where core services are independently deployable.

Key Changes:
- Core Kernel: Infrastructure only (no business logic)
- Core Services: Auth, Identity, Authz, Audit as separate microservices
  - Each service has own entry point (cmd/{service}/)
  - Each service has own gRPC server and database schema
  - Services register with Consul for service discovery
- API Gateway: Moved from Epic 8 to Epic 1 as core infrastructure
  - Single entry point for all external traffic
  - Handles routing, JWT validation, rate limiting, CORS
- Service Discovery: Consul as primary mechanism (ADR-0033)
- Database Pattern: Per-service connections with schema isolation

Documentation Updates:
- Updated all 9 architecture documents
- Updated 4 ADRs and created 2 new ADRs (API Gateway, Service Discovery)
- Rewrote Epic 1: Core Kernel & Infrastructure (infrastructure only)
- Rewrote Epic 2: Core Services (Auth, Identity, Authz, Audit as services)
- Updated Epic 3-8 stories for service architecture
- Updated plan.md, playbook.md, requirements.md, index.md
- Updated all epic READMEs and story files

New ADRs:
- ADR-0032: API Gateway Strategy
- ADR-0033: Service Discovery Implementation (Consul)

New Stories:
- Epic 1.7: Service Client Interfaces
- Epic 1.8: API Gateway Implementation

docs/content/architecture/component-relationships.md

@@ -32,10 +32,8 @@ graph TD
         Scheduler[Scheduler]
     end
     
-    subgraph "Security Layer"
-        Auth[Auth Service]
-        Authz[Authz Service]
-        Audit[Audit Service]
+    subgraph "Service Registry"
+        Registry[Service Registry<br/>Consul]
     end
     
     subgraph "Observability Layer"
@@ -52,17 +50,14 @@ graph TD
     DI --> Cache
     DI --> EventBus
     DI --> Scheduler
-    DI --> Auth
-    DI --> Authz
-    DI --> Audit
     DI --> Metrics
     DI --> Health
     DI --> Tracer
+    DI --> Registry
     
-    Auth --> DB
-    Authz --> DB
-    Authz --> Cache
-    Audit --> DB
+    Registry --> Auth
+    Registry --> Authz
+    Registry --> Audit
     
     DB --> Tracer
     Cache --> Tracer
@@ -73,9 +68,9 @@ graph TD
     style Auth fill:#ff6b6b,stroke:#c92a2a,stroke-width:2px,color:#fff
 ```
 
-## Module to Core Integration
+## Service to Service Integration
 
-Modules (services) integrate with core services through service client interfaces. All communication uses gRPC or HTTP.
+Feature services integrate with core services through service client interfaces. All communication uses gRPC (primary) or HTTP (fallback). Services discover each other via the service registry (Consul).
 
 ```mermaid
 graph LR
@@ -86,10 +81,14 @@ graph LR
     end
     
     subgraph "Service Clients"
-        AuthClient[Auth Service Client]
-        AuthzClient[Authz Service Client]
-        IdentityClient[Identity Service Client]
-        AuditClient[Audit Service Client]
+        AuthClient[Auth Service Client<br/>gRPC]
+        AuthzClient[Authz Service Client<br/>gRPC]
+        IdentityClient[Identity Service Client<br/>gRPC]
+        AuditClient[Audit Service Client<br/>gRPC]
+    end
+    
+    subgraph "Service Registry"
+        Registry[Consul<br/>Service Discovery]
     end
     
     subgraph "Core Services"
@@ -117,6 +116,16 @@ graph LR
     ModuleService --> EventBusService
     ModuleService --> CacheService
     
+    AuthClient -->|Discover| Registry
+    AuthzClient -->|Discover| Registry
+    IdentityClient -->|Discover| Registry
+    AuditClient -->|Discover| Registry
+    
+    Registry --> AuthService
+    Registry --> AuthzService
+    Registry --> IdentityService
+    Registry --> AuditService
+    
     AuthClient --> AuthService
     AuthzClient --> AuthzService
     IdentityClient --> IdentityService
@@ -127,7 +136,8 @@ graph LR
     EventBusService --> QueueClient
     
     style ModuleService fill:#7b68ee,stroke:#5a4fcf,stroke-width:2px,color:#fff
-    style AuthService fill:#4a90e2,stroke:#2e5c8a,stroke-width:2px,color:#fff
+    style Registry fill:#50c878,stroke:#2e7d4e,stroke-width:3px,color:#fff
+    style AuthService fill:#ff6b6b,stroke:#c92a2a,stroke-width:2px,color:#fff
     style DBClient fill:#50c878,stroke:#2e7d4e,stroke-width:2px,color:#fff
     style ServiceClients fill:#50c878,stroke:#2e7d4e,stroke-width:2px,color:#fff
 ```