chore: import upstream snapshot with attribution

apps/webapp/app/utils/computeBucket.ts

@@ -0,0 +1,15 @@
+/**
+ * Deterministic 0-99 bucket for an org id, stable across processes and deploys.
+ * FNV-1a (non-crypto): we only need determinism + uniform spread, not collision
+ * resistance. Used for nested percentage rollout: `hashBucket(orgId) < percentage`.
+ * Ramping the percentage down keeps a strict subset (the low buckets), so an org
+ * never flaps in and out as the dial moves.
+ */
+export function hashBucket(orgId: string): number {
+  let hash = 0x811c9dc5; // FNV offset basis
+  for (let i = 0; i < orgId.length; i++) {
+    hash ^= orgId.charCodeAt(i);
+    hash = Math.imul(hash, 0x01000193) >>> 0;
+  }
+  return hash % 100;
+}