[rbev]

Separate primary and audit SQL schemas

• Keep primary and audit tables in separate default schemas rather than supporting shared-schema installations.
• To ensure that no data loss occurs if a misconfiguration points both audit and error at the same schema it is now checked before making changes.

Why

The schema default was to share the same schema, however there was no testing that ensures this is actually supported.

For SQL Server and PostgreSQL:

• Default Database/Schema to psw_sc for primary instances and psw_audit for audit instances when the setting is absent or blank.
• Fail setup before applying migrations if the target schema contains the other instance's migration history table. Primary instances reject __AuditMigrationsHistory; audit instances reject __EFMigrationsHistory.
• Allow the other instance's migration history table in a different schema in the same database.

Custom schema names remain supported. Operators must create the schema and grant the configured user rights before running setup. Setup does not create schemas or move data.

Update persistence manifests, default-schema telemetry, and documentation to match.