fix(protect-dynamodb): use cast_as === 'json' not 'jsonb'

The branch reconstructing the SteVec storage payload from DynamoDB
attributes was gated on `cast_as === 'jsonb'`, but protect-ffi's
`CastAs` union has no `'jsonb'` member — the value the schema emits
for JSON columns is `'json'`. The branch was dead, so JSON / ste_vec
columns were silently rebuilt as a scalar `{k:'ct', c}` payload,
losing the `sv` array on the way back out.

The sibling `packages/stack/src/dynamodb/helpers.ts` already uses
`'json'` correctly — the two files had drifted.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: 2 people

packages/protect-dynamodb/src/helpers.ts

@@ -186,7 +186,7 @@ export function toItemWithEqlPayloads(
       // Worth noting, that encryptConfig.columns[columnName] will be undefined if isNested is true.
       if (
         !isNested &&
-        encryptConfig.columns[columnName].cast_as === 'jsonb' &&
+        encryptConfig.columns[columnName].cast_as === 'json' &&
         encryptConfig.columns[columnName].indexes.ste_vec
       ) {
         return {