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/epic1/1.1-enhanced-di-container.md

@@ -10,10 +10,12 @@
 - **Dependencies**: 0.5
 
 ## Goal
-Extend the DI container to provide all core infrastructure services with proper lifecycle management, dependency resolution, and service override support.
+Extend the DI container to provide core kernel infrastructure services only (no business logic services) with proper lifecycle management, dependency resolution, and service override support.
 
 ## Description
-This story extends the basic DI container to support all core services including database, health checks, metrics, and error bus. The container must handle service initialization order, lifecycle management, and provide a clean way to override services for testing.
+This story extends the basic DI container to support core kernel services only: config, logger, health checks, metrics, error bus, observability, and service registry. The container must handle service initialization order, lifecycle management, and provide a clean way to override services for testing.
+
+**Note:** Business services (Auth, Identity, Authz, Audit) are NOT in the core kernel. They are separate services implemented in Epic 2.
 
 ## Deliverables
 
@@ -25,13 +27,16 @@ This story extends the basic DI container to support all core services including
 - Error handling during initialization
 
 ### 2. Provider Functions (`internal/di/providers.go`)
-Complete provider functions for all core services:
+Complete provider functions for core kernel services only:
 - `ProvideConfig() fx.Option` - Configuration provider
 - `ProvideLogger() fx.Option` - Logger provider
-- `ProvideDatabase() fx.Option` - Ent database client provider
 - `ProvideHealthCheckers() fx.Option` - Health check registry provider
 - `ProvideMetrics() fx.Option` - Prometheus metrics registry provider
 - `ProvideErrorBus() fx.Option` - Error bus provider
+- `ProvideTracer() fx.Option` - OpenTelemetry tracer provider
+- `ProvideServiceRegistry() fx.Option` - Service registry provider (Consul)
+
+**Note:** Database provider is NOT in core kernel - each service will create its own database client.
 
 ### 3. Core Module (`internal/di/core_module.go`)
 - Export `CoreModule() fx.Option` that provides all core services
@@ -61,13 +66,15 @@ Complete provider functions for all core services:
    - Test lifecycle hooks
 
 ## Acceptance Criteria
-- [x] All core services are provided via DI container
+- [x] All core kernel services are provided via DI container
 - [x] Services are initialized in correct dependency order
 - [x] Lifecycle hooks work for all services
 - [x] Services can be overridden for testing
 - [x] DI container compiles without errors
 - [x] CoreModule can be imported and used
 - [x] Error handling works during initialization
+- [x] No business logic services in core kernel
+- [x] Service registry provider is included
 
 ## Related ADRs
 - [ADR-0003: Dependency Injection Framework](../../adr/0003-dependency-injection-framework.md)