feat(epic1): implement core infrastructure (stories 1.1-1.5)

Implemented Epic 1 core kernel and infrastructure stories:

Story 1.1: Enhanced DI Container
- Added providers for database, health, metrics, and error bus
- Extended CoreModule to include all core services

Story 1.2: Database Layer with Ent ORM
- Created Ent schema for User, Role, Permission, AuditLog entities
- Implemented many-to-many relationships (User-Role, Role-Permission)
- Created database client wrapper with connection pooling
- Added database provider to DI container with migration support

Story 1.3: Health Monitoring and Metrics System
- Implemented health check registry and interface
- Added database health checker
- Created Prometheus metrics system with HTTP instrumentation
- Added health and metrics providers to DI container

Story 1.4: Error Handling and Error Bus
- Implemented channel-based error bus
- Created ErrorPublisher interface
- Added error bus provider with lifecycle management

Story 1.5: HTTP Server Foundation
- Created HTTP server with Gin framework
- Implemented comprehensive middleware stack:
  - Request ID generation
  - Structured logging
  - Panic recovery with error bus integration
  - Prometheus metrics collection
  - CORS support
- Registered core routes: /healthz, /ready, /metrics
- Integrated with FX lifecycle for graceful shutdown

All components are integrated via DI container and ready for use.

internal/ent/schema/audit_log.go

@@ -0,0 +1,49 @@
+package schema
+
+import (
+	"time"
+
+	"entgo.io/ent"
+	"entgo.io/ent/schema/field"
+	"entgo.io/ent/schema/index"
+)
+
+// AuditLog holds the schema definition for the AuditLog entity.
+type AuditLog struct {
+	ent.Schema
+}
+
+// Fields of the AuditLog.
+func (AuditLog) Fields() []ent.Field {
+	return []ent.Field{
+		field.String("id").
+			Unique().
+			Immutable(),
+		field.String("actor_id").
+			NotEmpty().
+			Comment("ID of the user/actor performing the action"),
+		field.String("action").
+			NotEmpty().
+			Comment("Action performed (e.g., create, update, delete)"),
+		field.String("target_id").
+			Optional().
+			Comment("ID of the target resource"),
+		field.JSON("metadata", map[string]interface{}{}).
+			Optional().
+			Comment("Additional metadata as JSON"),
+		field.Time("timestamp").
+			Default(time.Now).
+			Immutable(),
+	}
+}
+
+// Indexes of the AuditLog.
+func (AuditLog) Indexes() []ent.Index {
+	return []ent.Index{
+		index.Fields("actor_id"),
+		index.Fields("target_id"),
+		index.Fields("timestamp"),
+		index.Fields("action"),
+	}
+}
+

internal/ent/schema/permission.go

@@ -0,0 +1,33 @@
+package schema
+
+import (
+	"entgo.io/ent"
+	"entgo.io/ent/schema/edge"
+	"entgo.io/ent/schema/field"
+)
+
+// Permission holds the schema definition for the Permission entity.
+type Permission struct {
+	ent.Schema
+}
+
+// Fields of the Permission.
+func (Permission) Fields() []ent.Field {
+	return []ent.Field{
+		field.String("id").
+			Unique().
+			Immutable(),
+		field.String("name").
+			Unique().
+			NotEmpty().
+			Comment("Format: module.resource.action"),
+	}
+}
+
+// Edges of the Permission.
+func (Permission) Edges() []ent.Edge {
+	return []ent.Edge{
+		edge.To("role_permissions", RolePermission.Type),
+	}
+}
+

internal/ent/schema/role.go

@@ -0,0 +1,40 @@
+package schema
+
+import (
+	"time"
+
+	"entgo.io/ent"
+	"entgo.io/ent/schema/edge"
+	"entgo.io/ent/schema/field"
+)
+
+// Role holds the schema definition for the Role entity.
+type Role struct {
+	ent.Schema
+}
+
+// Fields of the Role.
+func (Role) Fields() []ent.Field {
+	return []ent.Field{
+		field.String("id").
+			Unique().
+			Immutable(),
+		field.String("name").
+			Unique().
+			NotEmpty(),
+		field.String("description").
+			Optional(),
+		field.Time("created_at").
+			Default(time.Now).
+			Immutable(),
+	}
+}
+
+// Edges of the Role.
+func (Role) Edges() []ent.Edge {
+	return []ent.Edge{
+		edge.To("role_permissions", RolePermission.Type),
+		edge.To("user_roles", UserRole.Type),
+	}
+}
+

internal/ent/schema/role_permission.go

@@ -0,0 +1,35 @@
+package schema
+
+import (
+	"entgo.io/ent"
+	"entgo.io/ent/schema/edge"
+	"entgo.io/ent/schema/field"
+)
+
+// RolePermission holds the schema definition for the RolePermission entity (many-to-many relationship).
+type RolePermission struct {
+	ent.Schema
+}
+
+// Fields of the RolePermission.
+func (RolePermission) Fields() []ent.Field {
+	return []ent.Field{
+		field.String("role_id"),
+		field.String("permission_id"),
+	}
+}
+
+// Edges of the RolePermission.
+func (RolePermission) Edges() []ent.Edge {
+	return []ent.Edge{
+		edge.To("role", Role.Type).
+			Unique().
+			Required().
+			Field("role_id"),
+		edge.To("permission", Permission.Type).
+			Unique().
+			Required().
+			Field("permission_id"),
+	}
+}
+

internal/ent/schema/user.go

@@ -0,0 +1,44 @@
+package schema
+
+import (
+	"time"
+
+	"entgo.io/ent"
+	"entgo.io/ent/schema/edge"
+	"entgo.io/ent/schema/field"
+)
+
+// User holds the schema definition for the User entity.
+type User struct {
+	ent.Schema
+}
+
+// Fields of the User.
+func (User) Fields() []ent.Field {
+	return []ent.Field{
+		field.String("id").
+			Unique().
+			Immutable(),
+		field.String("email").
+			Unique().
+			NotEmpty(),
+		field.String("password_hash").
+			NotEmpty(),
+		field.Bool("verified").
+			Default(false),
+		field.Time("created_at").
+			Default(time.Now).
+			Immutable(),
+		field.Time("updated_at").
+			Default(time.Now).
+			UpdateDefault(time.Now),
+	}
+}
+
+// Edges of the User.
+func (User) Edges() []ent.Edge {
+	return []ent.Edge{
+		edge.To("user_roles", UserRole.Type),
+	}
+}
+

internal/ent/schema/user_role.go

@@ -0,0 +1,35 @@
+package schema
+
+import (
+	"entgo.io/ent"
+	"entgo.io/ent/schema/edge"
+	"entgo.io/ent/schema/field"
+)
+
+// UserRole holds the schema definition for the UserRole entity (many-to-many relationship).
+type UserRole struct {
+	ent.Schema
+}
+
+// Fields of the UserRole.
+func (UserRole) Fields() []ent.Field {
+	return []ent.Field{
+		field.String("user_id"),
+		field.String("role_id"),
+	}
+}
+
+// Edges of the UserRole.
+func (UserRole) Edges() []ent.Edge {
+	return []ent.Edge{
+		edge.To("user", User.Type).
+			Unique().
+			Required().
+			Field("user_id"),
+		edge.To("role", Role.Type).
+			Unique().
+			Required().
+			Field("role_id"),
+	}
+}
+