sitesmith: alias tiny-invariant to a diagnostic shim

The prod build of tiny-invariant strips all failure messages, leaving
us with bare 'Error: Invariant failed' and no actionable info. Aliasing
the package to a shim that always emits the message + a stack-trace
console.error before throwing — so the next Craft.js invariant we hit
tells us which assertion (ERROR_NOT_IN_RESOLVER, ERROR_NOPARENT,
ERROR_INVALID_NODE_ID, etc.) is actually failing.

Temporary; will revert once the Sitesmith apply flow is stable.

craft/src/utils/tiny-invariant-shim.ts

@@ -0,0 +1,17 @@
+/**
+ * Diagnostic shim for tiny-invariant. The prod tiny-invariant strips
+ * the failure message, so we lose the actual reason for any Craft.js
+ * Invariant. Aliasing tiny-invariant -> this shim restores it.
+ */
+export default function invariant(condition: unknown, message?: string | (() => string)): asserts condition {
+  if (condition) return;
+  const provided = typeof message === 'function' ? message() : message;
+  const value = provided ? `Invariant failed: ${provided}` : 'Invariant failed';
+  // Surface the message + stack to the console BEFORE throwing so even
+  // an uncaught throw leaves a trace we can read.
+  // eslint-disable-next-line no-console
+  console.error('[CRAFT INVARIANT]', value);
+  // eslint-disable-next-line no-console
+  console.error(new Error('stack-only').stack);
+  throw new Error(value);
+}