IFTA returns are due on fixed dates (Apr30/Jul31/Oct31/Jan31) and every
interstate carrier (op code A, ~628k sendable) files 4x/year forever -- pure
recurring revenue, no per-carrier deadline data needed.
- build_ifta_quarterly_campaign.py: self-gates to the reminder window (~21d
before each deadline), selects interstate carriers, mints the same-day coupon,
builds+schedules the campaign reusing build_trucking_campaigns plumbing (DRY:
one source of truth for sending/suppression/coupon). Per-quarter cycle reset
(ifta_reminder_cycle marker) so each quarter re-reminds the full pool; marks
ifta_reminded_at to avoid double-sends within a cycle.
- ifta_quarterly_reminder.html: deadline + penalties + 'we do the math' + coupon
+ CAN-SPAM. Listmonk source campaign id 469.
- migration 094: fmcsa_carriers.ifta_reminded_at column + partial index.
Verified: deadline/window logic correct, imports reuse tc helpers, migration
applied on prod.