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/files/[...key]/route.ts

@@ -1,38 +1,60 @@
 import { NextResponse } from "next/server"
 import { getSessionUser } from "@/lib/session"
-import { readFile, contentTypeForKey } from "@/lib/storage"
+import { getEffectiveOwnerId } from "@/lib/account"
+import { readFile, contentTypeForKey, usingSpaces, presignGetUrl } from "@/lib/storage"
 
 // Only these image types are safe to render inline from our origin. Everything
 // else (including svg, html, documents) is forced to download as an attachment.
 const INLINE_EXTENSIONS = ["png", "jpg", "jpeg", "gif", "webp"]
 
-// Auth-gated file serving. Storage keys are namespaced by user id
-// (`<userId>/<scope>/<file>`), so a file belongs to the requester iff the key's
-// first segment equals their session user id.
+// Auth-gated file serving. Storage keys are namespaced by the portfolio's owner
+// id (`<ownerId>/<scope>/<file>`), so a file belongs to the requester iff the
+// key's first segment equals their EFFECTIVE owner id — this lets active team
+// members view the owner's files while preserving isolation between accounts.
+//
+// When object storage (Spaces) is configured we issue a short-lived presigned
+// redirect so the bytes stream straight from the bucket to the browser instead
+// of through the app. The auth + ownership checks below still gate every request
+// (the presigned URL is only minted for the rightful owner and expires quickly).
 export async function GET(_: Request, { params }: { params: Promise<{ key: string[] }> }) {
   const user = await getSessionUser()
   if (!user) return NextResponse.json({ error: "Unauthorized" }, { status: 401 })
 
+  const ownerId = await getEffectiveOwnerId(user.id)
+
   const { key: segments } = await params
 
   // Reject traversal / malformed segments (no double-decode — params are already decoded).
   const badSegment = segments.some(
     (s) => s === "" || s === "." || s === ".." || s.includes("/") || s.includes("\\")
   )
-  // Ownership: the first path segment must be EXACTLY the caller's user id.
-  if (badSegment || segments[0] !== user.id) {
+  // Ownership: the first path segment must be EXACTLY the caller's effective owner id.
+  if (badSegment || segments[0] !== ownerId) {
     return NextResponse.json({ error: "Forbidden" }, { status: 403 })
   }
 
   const key = segments.join("/")
+  const ext = key.split(".").pop()?.toLowerCase() ?? ""
+  const disposition = INLINE_EXTENSIONS.includes(ext) ? "inline" : "attachment"
+  const basename = (key.split("/").pop() ?? "file").replace(/["\\\r\n]/g, "")
 
+  // Object storage: redirect to a presigned URL (bytes served by Spaces).
+  if (usingSpaces()) {
+    try {
+      const url = await presignGetUrl(key, { disposition, filename: basename, expiresIn: 3600 })
+      const res = NextResponse.redirect(url, 302)
+      // Let the browser reuse the redirect for a while (< the URL's TTL) so
+      // repeat views skip the app hop entirely, without outliving the signature.
+      res.headers.set("Cache-Control", "private, max-age=1800")
+      return res
+    } catch {
+      return NextResponse.json({ error: "Not found" }, { status: 404 })
+    }
+  }
+
+  // Local-disk fallback: stream the bytes through the app.
   try {
     const buffer = await readFile(key)
-
-    const ext = key.split(".").pop()?.toLowerCase() ?? ""
-    const disposition = INLINE_EXTENSIONS.includes(ext) ? "inline" : "attachment"
-    const basename = (key.split("/").pop() ?? "file").replace(/["\\\r\n\x00-\x1f]/g, "")
-
     return new NextResponse(new Uint8Array(buffer), {
       headers: {
         "Content-Type": contentTypeForKey(key),