fix(proxy): load clipper-lib via require in ESM

The compiled server runs Node's native ESM loader, where the CommonJS
namespace object nests the real exports under 'default', so
'import * as ClipperLib' left JoinType undefined and crashed with
offset. Match the existing vtracer pattern and require() the package
instead.

apps/proxy/src/routes/svgShape.ts

@@ -1,7 +1,12 @@
-import * as ClipperLib from 'clipper-lib';
+import { createRequire } from 'module';
 import svgpath from 'svgpath';
 import type { TracedShape } from '@tts/shared';
 
+// clipper-lib is a CommonJS package; load it via require so the enums and
+// classes resolve under Node's native ESM loader without a `default` unwrap.
+const require = createRequire(import.meta.url);
+const ClipperLib = require('clipper-lib') as typeof import('clipper-lib');
+
 /** Number of samples per cubic bezier when flattening curves to polylines. */
 const CURVE_STEPS = 12;