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/stories/epic1/README.md

@@ -1,19 +1,23 @@
 # Epic 1: Core Kernel & Infrastructure
 
 ## Overview
-Extend DI container to support all core services, implement database layer with Ent ORM, build health monitoring and metrics system, create error handling and error bus, establish HTTP server with comprehensive middleware stack, and integrate OpenTelemetry for distributed tracing.
+Build the core kernel infrastructure (config, logger, DI, health, metrics, observability) with **no business logic**. Implement API Gateway as core infrastructure component. Create service client interfaces and service registry foundation. Establish HTTP/gRPC server foundations that services will use.
+
+**Note:** This epic focuses on infrastructure only. Business services (Auth, Identity, Authz, Audit) are implemented in Epic 2 as separate microservices.
 
 ## Stories
 
 ### 1.1 Enhanced Dependency Injection Container
 - [Story: 1.1 - Enhanced DI Container](./1.1-enhanced-di-container.md)
-- **Goal:** Extend the DI container to provide all core infrastructure services with proper lifecycle management.
-- **Deliverables:** Extended DI container, provider functions for all services, core module export
+- **Goal:** Extend the DI container to provide core kernel infrastructure services only (no business logic) with proper lifecycle management.
+- **Deliverables:** Extended DI container, provider functions for core kernel services only, core module export
 
-### 1.2 Database Layer with Ent ORM
-- [Story: 1.2 - Database Layer](./1.2-database-layer.md)
-- **Goal:** Set up a complete database layer using Ent ORM with core domain entities, migrations, and connection management.
-- **Deliverables:** Ent schema, core entities, database client, migrations, connection pooling
+### 1.2 Database Client Foundation
+- [Story: 1.2 - Database Client Foundation](./1.2-database-layer.md)
+- **Goal:** Set up database client foundation for services. Each service will have its own database connection and schema.
+- **Deliverables:** Database client wrapper with schema support, connection pooling, per-service connection management
+
+**Note:** Core domain entities (User, Role, Permission, AuditLog) are implemented in Epic 2 as part of their respective services.
 
 ### 1.3 Health Monitoring and Metrics System
 - [Story: 1.3 - Health & Metrics](./1.3-health-metrics-system.md)
@@ -25,31 +29,47 @@ Extend DI container to support all core services, implement database layer with
 - **Goal:** Implement centralized error handling with an error bus that captures, logs, and optionally reports all application errors.
 - **Deliverables:** Error bus interface, channel-based implementation, panic recovery middleware
 
-### 1.5 HTTP Server Foundation with Middleware Stack
-- [Story: 1.5 - HTTP Server](./1.5-http-server.md)
-- **Goal:** Create a production-ready HTTP server with comprehensive middleware for security, observability, and error handling.
-- **Deliverables:** HTTP server, comprehensive middleware stack, core routes, FX lifecycle integration
+### 1.5 HTTP/gRPC Server Foundation
+- [Story: 1.5 - HTTP/gRPC Server Foundation](./1.5-http-server.md)
+- **Goal:** Create HTTP and gRPC server foundation that services can use. Each service will have its own server instance.
+- **Deliverables:** HTTP server foundation, gRPC server foundation, common middleware, lifecycle management
 
 ### 1.6 OpenTelemetry Distributed Tracing
 - [Story: 1.6 - OpenTelemetry](./1.6-opentelemetry.md)
-- **Goal:** Integrate OpenTelemetry for distributed tracing across the platform to enable observability in production.
-- **Deliverables:** OpenTelemetry setup, HTTP instrumentation, database instrumentation, trace-log correlation
+- **Goal:** Integrate OpenTelemetry for distributed tracing across all services to enable observability in production.
+- **Deliverables:** OpenTelemetry setup, HTTP instrumentation, gRPC instrumentation, database instrumentation, trace-log correlation
+
+### 1.7 Service Client Interfaces
+- [Story: 1.7 - Service Client Interfaces](./1.7-service-client-interfaces.md)
+- **Goal:** Create service client interfaces for all core services to enable microservices communication.
+- **Deliverables:** Service client interfaces in `pkg/services/`, service client factory, gRPC/HTTP client implementations
+
+### 1.8 API Gateway Implementation
+- [Story: 1.8 - API Gateway](./1.8-api-gateway.md)
+- **Goal:** Implement API Gateway as core infrastructure component that routes all external traffic to backend services.
+- **Deliverables:** API Gateway service entry point, gateway implementation with routing, JWT validation, rate limiting, service discovery integration
 
 ## Deliverables Checklist
-- [x] DI container with all core services
-- [x] Database client with Ent schema
+- [x] DI container with core kernel services only (no business logic)
+- [x] Database client foundation (per-service connections)
 - [x] Health and metrics endpoints functional
 - [x] Error bus captures and logs errors
-- [x] HTTP server with middleware stack
+- [x] HTTP/gRPC server foundation for services
 - [x] Basic observability with OpenTelemetry
+- [x] Service client interfaces defined
+- [x] API Gateway service (core infrastructure)
+- [x] Basic service registry implementation (Consul)
 
 ## Acceptance Criteria
-- `GET /healthz` returns 200
-- `GET /ready` checks DB connectivity
+- `GET /healthz` returns 200 for all services
+- `GET /ready` checks service health
 - `GET /metrics` exposes Prometheus metrics
 - Panic recovery logs errors via error bus
-- Database migrations run on startup
-- HTTP requests are traced with OpenTelemetry
+- HTTP/gRPC requests are traced with OpenTelemetry
+- API Gateway routes requests to backend services
+- Service client interfaces are defined
+- Services can register with Consul
+- No business logic services in Epic 1
 
 ## Implementation Summary