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/vendors/[id]/route.ts

@@ -4,11 +4,16 @@ import { db } from "@/lib/db"
 import { vendors } from "@/lib/db/schema"
 import { getSessionUser } from "@/lib/session"
 import { ownsProperty } from "@/lib/db/ownership"
+import { getAccountContext } from "@/lib/account"
 
 export async function PATCH(request: Request, { params }: { params: Promise<{ id: string }> }) {
   const user = await getSessionUser()
   if (!user) return NextResponse.json({ error: "Unauthorized" }, { status: 401 })
 
+  const ctx = await getAccountContext(user.id)
+  const ownerId = ctx.ownerId
+  if (!ctx.canWrite) return NextResponse.json({ error: "Forbidden" }, { status: 403 })
+
   const { id } = await params
   const body = await request.json()
 
@@ -20,7 +25,7 @@ export async function PATCH(request: Request, { params }: { params: Promise<{ id
   if (body.notes !== undefined) allowed.notes = body.notes || null
   if (body.property_id !== undefined) allowed.property_id = body.property_id || null
 
-  if (!(await ownsProperty(user.id, allowed.property_id))) {
+  if (!(await ownsProperty(ownerId, allowed.property_id))) {
     return NextResponse.json({ error: "Invalid reference" }, { status: 403 })
   }
 
@@ -28,7 +33,7 @@ export async function PATCH(request: Request, { params }: { params: Promise<{ id
     const [data] = await db
       .update(vendors)
       .set(allowed)
-      .where(and(eq(vendors.id, id), eq(vendors.user_id, user.id)))
+      .where(and(eq(vendors.id, id), eq(vendors.user_id, ownerId)))
       .returning()
 
     return NextResponse.json(data)
@@ -40,7 +45,12 @@ export async function PATCH(request: Request, { params }: { params: Promise<{ id
 export async function DELETE(_: Request, { params }: { params: Promise<{ id: string }> }) {
   const user = await getSessionUser()
   if (!user) return NextResponse.json({ error: "Unauthorized" }, { status: 401 })
+
+  const ctx = await getAccountContext(user.id)
+  const ownerId = ctx.ownerId
+  if (!ctx.canWrite) return NextResponse.json({ error: "Forbidden" }, { status: 403 })
+
   const { id } = await params
-  await db.delete(vendors).where(and(eq(vendors.id, id), eq(vendors.user_id, user.id)))
+  await db.delete(vendors).where(and(eq(vendors.id, id), eq(vendors.user_id, ownerId)))
   return NextResponse.json({ ok: true })
 }