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>

app/api/paypal/cancel/route.ts

@@ -0,0 +1,32 @@
+import { NextResponse } from "next/server"
+import { eq } from "drizzle-orm"
+import { db } from "@/lib/db"
+import { profiles } from "@/lib/db/schema"
+import { getSessionUser } from "@/lib/session"
+import { cancelSubscription } from "@/lib/paypal/checkout"
+
+// Cancel the signed-in user's PayPal subscription. The account keeps access
+// until the paid period ends; the BILLING.SUBSCRIPTION.CANCELLED webhook does
+// the final downgrade to starter.
+export async function POST() {
+  const user = await getSessionUser()
+  if (!user) return NextResponse.json({ error: "Unauthorized" }, { status: 401 })
+
+  const profile = await db.query.profiles.findFirst({
+    where: eq(profiles.id, user.id),
+    columns: { paypal_subscription_id: true },
+  })
+  if (!profile?.paypal_subscription_id) {
+    return NextResponse.json({ error: "No PayPal subscription to cancel" }, { status: 400 })
+  }
+
+  const ok = await cancelSubscription(profile.paypal_subscription_id)
+  if (!ok) return NextResponse.json({ error: "PayPal cancellation failed" }, { status: 502 })
+
+  await db
+    .update(profiles)
+    .set({ subscription_status: "canceled" })
+    .where(eq(profiles.id, user.id))
+
+  return NextResponse.json({ ok: true })
+}