trucking: same-day expiring coupon to drive immediate conversion

The sales we got came at $79 + a 24hr coupon; cutting MCS-150 to $39 flat
removed urgency and conversions did NOT improve (a permanent low price sets a
new anchor and lets people defer). Restore the higher anchor and let an
expiring discount create the now-or-lose-it decision.

- Restore MCS-150 anchor $39 -> $79 (catalog single source + regenerated).
- build_trucking_campaigns.py: mint ONE random 5-letter coupon per send-day
  (40% off, valid through 23:59:59 ET that day) into the existing discount_codes
  table; inject coupon_code/pct/expires + a ?code= LP link into every email.
  Idempotent per day; service-fee-only scope (gov/pass-through fees never cut).
- Listmonk MCS-150 (186) + Inactive USDOT (188) templates: lead with the
  struck-through anchor + sale price + code + 'expires tonight', and point the
  primary CTA at the order page (with code) instead of the 'free check' tool.
- OrderPriceBanner: validates ?code= via /api/v1/discount and shows
  was/now + expiry; Wizard forwards the code to order creation.
- Verified: code gen, expiry math, scope enforcement, discount API
  (40% off $79 = $47.40), site+api builds clean.

site/src/lib/service-catalog.generated.ts

@@ -61,7 +61,7 @@ export const SERVICE_META: Record<string, ServiceMeta> = {
   "ky-kyu-registration": { name: "KY Weight-Distance Tax Setup", price_cents: 10900, gov_fee_label: "KYU weight-distance account fees (state, billed at cost)" },
   "llc-formation": { name: "LLC Formation", price_cents: 19900 },
   "mc-authority": { name: "MC Operating Authority Application", price_cents: 19900, gov_fee_label: "FMCSA operating authority application fee" },
-  "mcs150-update": { name: "MCS-150 Biennial Update", price_cents: 3900 },
+  "mcs150-update": { name: "MCS-150 Biennial Update", price_cents: 7900 },
   "medicare-enrollment": { name: "Medicare Enrollment (PECOS)", price_cents: 69900 },
   "name-reservation-nv": { name: "Nevada Name Reservation (90 days)", price_cents: 7900, gov_fee_label: "Nevada SOS name reservation fee" },
   "name-reservation-tx": { name: "Texas Name Reservation (Form 501, 120 days)", price_cents: 7900, gov_fee_label: "Texas SOS name reservation fee (Form 501)" },