fix(test): add polyfill shims for vitest environment

web/src/tests/mocks/buffer-shim.ts

@@ -0,0 +1,2 @@
+import { Buffer } from 'buffer';
+export default Buffer;

web/src/tests/mocks/global-shim.ts

@@ -0,0 +1 @@
+export default globalThis;

web/src/tests/mocks/process-shim.ts

@@ -0,0 +1 @@
+export default { env: {} };