fix(kit): use path.basename/dirname in embeddedMigrations to fix Windows path separators

On Windows, snapshot paths use backslash separators. The previous
entry.split('/')[...length - 2] approach returns undefined when the
path contains only backslashes, causing migrations.js to import from
'./undefined/migration.sql'.

Replace with path.basename(path.dirname(entry)) which correctly
extracts the parent folder name on all platforms.

Author: sleitor

drizzle-kit/src/cli/commands/generate-common.ts

@@ -97,7 +97,7 @@ export const embeddedMigrations = (snapshots: string[], driver?: Driver) => {
 	const migrations: Record<string, string> = {};
 
 	snapshots.forEach((entry, idx) => {
-		const prefix = entry.split('/')[entry.split('/').length - 2];
+		const prefix = path.basename(path.dirname(entry));
 		const importName = idx.toString().padStart(4, '0');
 		content += `import m${importName} from './${prefix}/migration.sql';\n`;
 		migrations[prefix] = importName;