Each decorator now bundles its schema prereqs alongside its code via
DecoratorPrereq (additive CREATE-IF-NOT-EXISTS) and ReshapeStep
(non-idempotent reshape gated on a detectSql probe).
applyDecoratorMigrations<Decorators...>(table, probe, exec, recorder)
walks the listed decorators at startup, runs every PREREQ, runs every
reshape step whose probe returns false. Database-agnostic — consumer
wires probe/exec to their DbClient. SCHEMA_MIGRATIONS_TABLE_SQL is
provided for observability; the detect-probe is the source of truth.
TemporalRepository ships add_valid_from / add_valid_until /
drop_unique_entity_id / composite_unique (UNIQUE(entity_id, valid_until)
so close-then-insert can run in a deferred-FK transaction).
AuditLogRepository ships the audit_log CREATE TABLE.
ScopeGuardRepository ships nothing — exposes empty PREREQ + zero-length
RESHAPE_STEPS so it can be listed in applyDecoratorMigrations alongside
the schema-touching decorators without SFINAE.
Closes#12
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
