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/module-integration-patterns.md

@@ -6,7 +6,7 @@ This document explains how modules integrate with the core platform, focusing on
 
 ## Overview
 
-Modules are independent services that extend the platform's functionality. They integrate with the core platform through well-defined interfaces, service clients, and a standardized initialization process. Each module operates as an independent service while leveraging core platform capabilities.
+Modules are implemented as independent services that extend the platform's functionality. They integrate with core services through service client interfaces, service discovery (Consul), and a standardized initialization process. Each module operates as an independent service with its own entry point, database connection, and deployment while leveraging core platform capabilities.
 
 ## Key Concepts
 
@@ -94,7 +94,7 @@ sequenceDiagram
         DB-->>Module: Migrations registered
         
         Module->>ServiceRegistry: Register service
-        ServiceRegistry->>ServiceRegistry: Register with registry
+        ServiceRegistry->>ServiceRegistry: Register with Consul
         ServiceRegistry-->>Module: Service registered
         
         Module->>Module: OnStart hook (optional)