Remove UniqueConstraint('id') from all create_table calls in the initial
migration (40 occurrences) and the bulk constraint additions from the
superadmin migration (43 create + 43 drop). These were redundant with
PrimaryKeyConstraint('id') which already guarantees uniqueness.
Also removes duplicate unique enforcement on superadmins.email and
superadmin_sessions.token (kept the unique indexes, dropped the
table-level UniqueConstraints).
Fixes the root cause in BaseModel by removing unique=True from the id
column definition, which was causing Alembic autogenerate to produce
these redundant constraints.
Renames idx_cert_audit_org to ix_certificate_audit_logs_organization_id
to follow Alembic naming conventions.