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/user/user.go

@@ -0,0 +1,127 @@
+// Code generated by ent, DO NOT EDIT.
+
+package user
+
+import (
+	"time"
+
+	"entgo.io/ent/dialect/sql"
+	"entgo.io/ent/dialect/sql/sqlgraph"
+)
+
+const (
+	// Label holds the string label denoting the user type in the database.
+	Label = "user"
+	// FieldID holds the string denoting the id field in the database.
+	FieldID = "id"
+	// FieldEmail holds the string denoting the email field in the database.
+	FieldEmail = "email"
+	// FieldPasswordHash holds the string denoting the password_hash field in the database.
+	FieldPasswordHash = "password_hash"
+	// FieldVerified holds the string denoting the verified field in the database.
+	FieldVerified = "verified"
+	// FieldCreatedAt holds the string denoting the created_at field in the database.
+	FieldCreatedAt = "created_at"
+	// FieldUpdatedAt holds the string denoting the updated_at field in the database.
+	FieldUpdatedAt = "updated_at"
+	// EdgeUserRoles holds the string denoting the user_roles edge name in mutations.
+	EdgeUserRoles = "user_roles"
+	// Table holds the table name of the user in the database.
+	Table = "users"
+	// UserRolesTable is the table that holds the user_roles relation/edge.
+	UserRolesTable = "user_roles"
+	// UserRolesInverseTable is the table name for the UserRole entity.
+	// It exists in this package in order to avoid circular dependency with the "userrole" package.
+	UserRolesInverseTable = "user_roles"
+	// UserRolesColumn is the table column denoting the user_roles relation/edge.
+	UserRolesColumn = "user_user_roles"
+)
+
+// Columns holds all SQL columns for user fields.
+var Columns = []string{
+	FieldID,
+	FieldEmail,
+	FieldPasswordHash,
+	FieldVerified,
+	FieldCreatedAt,
+	FieldUpdatedAt,
+}
+
+// ValidColumn reports if the column name is valid (part of the table columns).
+func ValidColumn(column string) bool {
+	for i := range Columns {
+		if column == Columns[i] {
+			return true
+		}
+	}
+	return false
+}
+
+var (
+	// EmailValidator is a validator for the "email" field. It is called by the builders before save.
+	EmailValidator func(string) error
+	// PasswordHashValidator is a validator for the "password_hash" field. It is called by the builders before save.
+	PasswordHashValidator func(string) error
+	// DefaultVerified holds the default value on creation for the "verified" field.
+	DefaultVerified bool
+	// DefaultCreatedAt holds the default value on creation for the "created_at" field.
+	DefaultCreatedAt func() time.Time
+	// DefaultUpdatedAt holds the default value on creation for the "updated_at" field.
+	DefaultUpdatedAt func() time.Time
+	// UpdateDefaultUpdatedAt holds the default value on update for the "updated_at" field.
+	UpdateDefaultUpdatedAt func() time.Time
+)
+
+// OrderOption defines the ordering options for the User queries.
+type OrderOption func(*sql.Selector)
+
+// ByID orders the results by the id field.
+func ByID(opts ...sql.OrderTermOption) OrderOption {
+	return sql.OrderByField(FieldID, opts...).ToFunc()
+}
+
+// ByEmail orders the results by the email field.
+func ByEmail(opts ...sql.OrderTermOption) OrderOption {
+	return sql.OrderByField(FieldEmail, opts...).ToFunc()
+}
+
+// ByPasswordHash orders the results by the password_hash field.
+func ByPasswordHash(opts ...sql.OrderTermOption) OrderOption {
+	return sql.OrderByField(FieldPasswordHash, opts...).ToFunc()
+}
+
+// ByVerified orders the results by the verified field.
+func ByVerified(opts ...sql.OrderTermOption) OrderOption {
+	return sql.OrderByField(FieldVerified, opts...).ToFunc()
+}
+
+// ByCreatedAt orders the results by the created_at field.
+func ByCreatedAt(opts ...sql.OrderTermOption) OrderOption {
+	return sql.OrderByField(FieldCreatedAt, opts...).ToFunc()
+}
+
+// ByUpdatedAt orders the results by the updated_at field.
+func ByUpdatedAt(opts ...sql.OrderTermOption) OrderOption {
+	return sql.OrderByField(FieldUpdatedAt, opts...).ToFunc()
+}
+
+// ByUserRolesCount orders the results by user_roles count.
+func ByUserRolesCount(opts ...sql.OrderTermOption) OrderOption {
+	return func(s *sql.Selector) {
+		sqlgraph.OrderByNeighborsCount(s, newUserRolesStep(), opts...)
+	}
+}
+
+// ByUserRoles orders the results by user_roles terms.
+func ByUserRoles(term sql.OrderTerm, terms ...sql.OrderTerm) OrderOption {
+	return func(s *sql.Selector) {
+		sqlgraph.OrderByNeighborTerms(s, newUserRolesStep(), append([]sql.OrderTerm{term}, terms...)...)
+	}
+}
+func newUserRolesStep() *sqlgraph.Step {
+	return sqlgraph.NewStep(
+		sqlgraph.From(Table, FieldID),
+		sqlgraph.To(UserRolesInverseTable, FieldID),
+		sqlgraph.Edge(sqlgraph.O2M, false, UserRolesTable, UserRolesColumn),
+	)
+}