feat(dbmanager): ✨ add support for existing SQL connections

* Introduced NewConnectionFromDB function to create connections from existing *sql.DB instances.
* Added ExistingDBProvider to wrap existing database connections for dbmanager features.
* Implemented tests for NewConnectionFromDB and ExistingDBProvider functionalities.

pkg/dbmanager/factory.go

@@ -1,6 +1,7 @@
 package dbmanager
 
 import (
+	"database/sql"
 	"fmt"
 
 	"github.com/bitechdev/ResolveSpec/pkg/dbmanager/providers"
@@ -49,3 +50,18 @@ func createProvider(dbType DatabaseType) (Provider, error) {
 // Provider is an alias to the providers.Provider interface
 // This allows dbmanager package consumers to use Provider without importing providers
 type Provider = providers.Provider
+
+// NewConnectionFromDB creates a new Connection from an existing *sql.DB
+// This allows you to use dbmanager features (ORM wrappers, health checks, etc.)
+// with a database connection that was opened outside of dbmanager
+//
+// Parameters:
+//   - name: A unique name for this connection
+//   - dbType: The database type (DatabaseTypePostgreSQL, DatabaseTypeSQLite, or DatabaseTypeMSSQL)
+//   - db: An existing *sql.DB connection
+//
+// Returns a Connection that wraps the existing *sql.DB
+func NewConnectionFromDB(name string, dbType DatabaseType, db *sql.DB) Connection {
+	provider := providers.NewExistingDBProvider(db, name)
+	return newSQLConnection(name, dbType, ConnectionConfig{Name: name, Type: dbType}, provider)
+}