chore: add changeset for protect-ffi upgrade

Author: coderdan

.changeset/upgrade-protect-ffi.md

@@ -0,0 +1,14 @@
+---
+"@cipherstash/protect": minor
+"@cipherstash/stack": minor
+"@cipherstash/schema": minor
+"@cipherstash/drizzle": patch
+---
+
+Upgrade protect-ffi to 0.21.0 and enable array_index_mode for searchable JSON
+
+- Upgrade `@cipherstash/protect-ffi` to 0.21.0 across all packages
+- Enable `array_index_mode: 'all'` on STE vec indexes so JSON array operations
+  (jsonb_array_elements, jsonb_array_length, array containment) work correctly
+- Delegate credential resolution entirely to protect-ffi's `withEnvCredentials`
+- Download latest EQL at build/runtime instead of bundling hardcoded SQL files