Replace openapi output-schema migration script with a drizzle SQL migration

The envelope unwrap is mechanical jsonb surgery, so it belongs in the
regular migration chain (db:migrate:prod) rather than a hand-run script:

- 0002_unwrap_openapi_output_envelope.sql rewrites envelope-shaped
  openapi tool output schemas to the payload schema (NULL when the
  envelope carried an empty data schema), using structural jsonb
  comparisons casted from the json column. Rows produced before the
  envelope existed don't match the predicates; re-running is a no-op.

Author: RhysSullivan

apps/cloud/drizzle/0002_unwrap_openapi_output_envelope.sql

@@ -0,0 +1,23 @@
+-- Unwrap the retired {status, headers, data} transport envelope from
+-- persisted OpenAPI tool output schemas. The runtime now returns the
+-- upstream payload as `data` (status/headers moved to the ToolResult
+-- `http` side channel), so persisted schemas must describe the payload
+-- only. Rows produced before the envelope existed (pre-#854) are already
+-- payload-shaped and don't match the predicates; re-running is a no-op.
+--
+-- The old producer emitted `"data": {}` when an operation declared no
+-- response schema; the new producer persists NULL for those.
+--
+-- output_schema is a `json` column, so structural comparisons cast to
+-- jsonb (json has no equality operator).
+UPDATE "tool"
+SET "output_schema" = CASE
+  WHEN ("output_schema" -> 'properties' -> 'data')::jsonb = '{}'::jsonb THEN NULL
+  ELSE "output_schema" -> 'properties' -> 'data'
+END
+WHERE "plugin_id" = 'openapi'
+  AND "output_schema" IS NOT NULL
+  AND "output_schema" ->> 'type' = 'object'
+  AND ("output_schema" -> 'required')::jsonb = '["status", "headers", "data"]'::jsonb
+  AND ("output_schema" -> 'properties' -> 'status')::jsonb = '{"type": "integer"}'::jsonb
+  AND ("output_schema" -> 'properties' -> 'headers')::jsonb = '{"type": "object", "additionalProperties": {"type": "string"}}'::jsonb;