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/actions/onboarding.ts

@@ -0,0 +1,15 @@
+"use server"
+
+import { redirect } from "next/navigation"
+import { eq } from "drizzle-orm"
+import { db } from "@/lib/db"
+import { profiles } from "@/lib/db/schema"
+import { getSessionUser } from "@/lib/session"
+
+/** Marks onboarding as finished and sends the user to the dashboard. */
+export async function completeOnboarding() {
+  const user = await getSessionUser()
+  if (!user) redirect("/login")
+  await db.update(profiles).set({ onboarding_completed: true }).where(eq(profiles.id, user.id))
+  redirect("/dashboard")
+}