Consolidate audit-fixes branch: webhooks, integrations, and deploy hardening

Batch commit of the pending working tree on security/audit-fixes-2026-07.
Major areas:
- Outbound webhooks / Zapier: schema + signed delivery with retries, public
  v1 API (REST-hook subscribe/unsubscribe), settings UI, cron drain.
- Deploy hardening: email via SMTP2GO (Resend fully removed), verified DB TLS
  (DATABASE_SSL=require + DATABASE_CA), storage fails loud in production when
  Spaces is unconfigured instead of silently using ephemeral disk.
- Integrations & features (concurrent work): accounting (QuickBooks/Xero),
  e-signature (DocuSign/Dropbox Sign), PayPal, geocoding/maps, onboarding,
  expanded legal pages.
- DB migrations 0006–0009.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lib/paypal/plans.ts

@@ -0,0 +1,28 @@
+import type { Plan } from "@/types"
+
+// PayPal billing-plan IDs, one per (plan, interval). Create them once with
+// `node scripts/paypal-setup-plans.mjs` and paste the printed IDs into the
+// environment. A plan/interval with no configured ID simply isn't offered.
+const PAYPAL_PLAN_IDS: Record<string, string | undefined> = {
+  "pro:month": process.env.PAYPAL_PRO_MONTHLY_PLAN_ID,
+  "pro:year": process.env.PAYPAL_PRO_YEARLY_PLAN_ID,
+  "landlord:month": process.env.PAYPAL_LANDLORD_MONTHLY_PLAN_ID,
+  "landlord:year": process.env.PAYPAL_LANDLORD_YEARLY_PLAN_ID,
+}
+
+/** Recurring plans PayPal can bill (lifetime is a one-time order, not a plan). */
+export const PAYPAL_RECURRING_PLANS = ["pro", "landlord"] as const
+
+export function getPaypalPlanId(plan: Plan, interval: "month" | "year"): string | undefined {
+  return PAYPAL_PLAN_IDS[`${plan}:${interval}`] || undefined
+}
+
+/** True when at least one PayPal-billable plan is configured. */
+export function anyPaypalPlanConfigured(): boolean {
+  return Object.values(PAYPAL_PLAN_IDS).some(Boolean)
+}
+
+/** Annual PayPal billing is offered only when both yearly plan IDs exist. */
+export function paypalAnnualEnabled(): boolean {
+  return Boolean(PAYPAL_PLAN_IDS["pro:year"] && PAYPAL_PLAN_IDS["landlord:year"])
+}