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/permission/permission.go

@@ -0,0 +1,83 @@
+// Code generated by ent, DO NOT EDIT.
+
+package permission
+
+import (
+	"entgo.io/ent/dialect/sql"
+	"entgo.io/ent/dialect/sql/sqlgraph"
+)
+
+const (
+	// Label holds the string label denoting the permission type in the database.
+	Label = "permission"
+	// FieldID holds the string denoting the id field in the database.
+	FieldID = "id"
+	// FieldName holds the string denoting the name field in the database.
+	FieldName = "name"
+	// EdgeRolePermissions holds the string denoting the role_permissions edge name in mutations.
+	EdgeRolePermissions = "role_permissions"
+	// Table holds the table name of the permission in the database.
+	Table = "permissions"
+	// RolePermissionsTable is the table that holds the role_permissions relation/edge.
+	RolePermissionsTable = "role_permissions"
+	// RolePermissionsInverseTable is the table name for the RolePermission entity.
+	// It exists in this package in order to avoid circular dependency with the "rolepermission" package.
+	RolePermissionsInverseTable = "role_permissions"
+	// RolePermissionsColumn is the table column denoting the role_permissions relation/edge.
+	RolePermissionsColumn = "permission_role_permissions"
+)
+
+// Columns holds all SQL columns for permission fields.
+var Columns = []string{
+	FieldID,
+	FieldName,
+}
+
+// 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 (
+	// NameValidator is a validator for the "name" field. It is called by the builders before save.
+	NameValidator func(string) error
+)
+
+// OrderOption defines the ordering options for the Permission 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()
+}
+
+// ByName orders the results by the name field.
+func ByName(opts ...sql.OrderTermOption) OrderOption {
+	return sql.OrderByField(FieldName, opts...).ToFunc()
+}
+
+// ByRolePermissionsCount orders the results by role_permissions count.
+func ByRolePermissionsCount(opts ...sql.OrderTermOption) OrderOption {
+	return func(s *sql.Selector) {
+		sqlgraph.OrderByNeighborsCount(s, newRolePermissionsStep(), opts...)
+	}
+}
+
+// ByRolePermissions orders the results by role_permissions terms.
+func ByRolePermissions(term sql.OrderTerm, terms ...sql.OrderTerm) OrderOption {
+	return func(s *sql.Selector) {
+		sqlgraph.OrderByNeighborTerms(s, newRolePermissionsStep(), append([]sql.OrderTerm{term}, terms...)...)
+	}
+}
+func newRolePermissionsStep() *sqlgraph.Step {
+	return sqlgraph.NewStep(
+		sqlgraph.From(Table, FieldID),
+		sqlgraph.To(RolePermissionsInverseTable, FieldID),
+		sqlgraph.Edge(sqlgraph.O2M, false, RolePermissionsTable, RolePermissionsColumn),
+	)
+}