Migration 0001 uses Base.metadata.create_all() which creates ALL tables
from current models.py, causing subsequent migrations (0015+) to fail
with "already exists" errors when they try to re-create constraints,
indexes, columns, and tables.
Three-layer fix:
1. migrations.py: detect fresh DB (no tables) and bootstrap via
create_all() + stamp head, bypassing all migrations entirely.
2. models.py: add EmailTemplate model, CheckConstraints to LandingPage,
and indexes to GuestPurchase so create_all() produces a complete
schema identical to running all 30 migrations sequentially.
3. Idempotency guards in migrations 0015-0030: _has_unique_constraint,
_has_table, _has_index, _has_column, _has_check_constraint checks
before DDL operations, protecting against re-runs via make migrate.
Fringg
bbd353ff38