stigmem-node's Postgres schema identifier handling required defensive quoting

Summary

### Impact Postgres backend schema identifiers were interpolated into SQL strings. In the reviewed code path the schema value is operator-controlled, but the pattern was unsafe if future call sites allowed tenant or request-controlled schema names. Impacted users are operators using the Postgres backend in affected versions. ### Patches Patched in 0.9.0a2. Schema identifier handling now uses defensive identifier quoting and validation-oriented regression coverage. ### Workarounds Before upgrading, only configure Postgres schema names from trusted deployment configuration and do not derive schema names from request, tenant, header, or user input. ### Upgrade Upgrade to the patched release: ```bash pip install --upgrade --pre stigmem-node ``` If developers install through the Stigmem meta-package instead, they should use the matching extra for deployments, for example: ```bash pip install --upgrade --pre 'stigmem[node]' ``` ### Resources - Release: https://github.com/eidetic-labs/stigmem/releases/tag/v0.9.0a2 - Changelog: https://github.com/eidetic-labs/stigmem/blob/v0.9.0a2/CHANGELOG.md#L14-L35 - Security policy and posture: https://github.com/eidetic-labs/stigmem/blob/v0.9.0a2/SECURITY.md