Security hardening from 2026-07-01 audit

- Exclude supabase/ from Docker build context (leaked service_role key file)
- /api/files: exact per-user namespace match + reject path traversal;
  storage resolveKey rejects ".."/"." segments (fixes cross-user file read)
- Add ownsProperty/Unit/Tenant checks to tenants, maintenance (landlord path),
  and documents (JSON branch, now field-whitelisted) create handlers
- Escape user data in follow-up + payment-link emails (reuse escapeHtml)
- Neutralize CSV formula injection in toCsv + export routes
- Tighter sign-in rate limit (10/min); env-gated email verification + sender
- Per-request nonce CSP; drop script-src 'unsafe-inline' (styles unchanged)
- Add input length bounds; validate follow-ups POST body

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/api/follow-ups/route.ts

@@ -3,6 +3,7 @@ import { desc, eq } from "drizzle-orm"
 import { db } from "@/lib/db"
 import { follow_up_rules, follow_up_log } from "@/lib/db/schema"
 import { getSessionUser } from "@/lib/session"
+import { followUpRuleSchema } from "@/lib/validations"
 
 export async function GET() {
   const user = await getSessionUser()
@@ -30,13 +31,16 @@ export async function POST(request: Request) {
   if (!user) return NextResponse.json({ error: "Unauthorized" }, { status: 401 })
 
   const body = await request.json()
-  const { type, name, trigger_days, message_template } = body
+  const parsed = followUpRuleSchema.safeParse(body)
+  if (!parsed.success) {
+    return NextResponse.json({ error: parsed.error.issues[0]?.message ?? "Invalid input" }, { status: 400 })
+  }
 
-  if (!type || !name) return NextResponse.json({ error: "type and name required" }, { status: 400 })
+  const { type, name, trigger_days, message_template } = parsed.data
 
   const [data] = await db
     .insert(follow_up_rules)
-    .values({ user_id: user.id, type, name, trigger_days: trigger_days ?? 3, message_template })
+    .values({ user_id: user.id, type, name, trigger_days, message_template })
     .returning()
 
   return NextResponse.json(data, { status: 201 })