docs: overhaul README and mark project proprietary

- Rewrite README: accurate current feature set (public API, webhooks/Zapier,
  PayPal, accounting sync, e-sign, team, branding, inspections, maps, ~30 tables,
  4 cron jobs), emoji section headers, clearer setup and security sections.
- Remove the inline env-variable example block; point to .env.example / DIGITALOCEAN.md.
- Fix stale "local disk" storage references to DigitalOcean Spaces.
- License: change MIT -> Proprietary; add LICENSE file and package.json "UNLICENSED".

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

LICENSE

@@ -0,0 +1,22 @@
+PROPRIETARY SOFTWARE LICENSE
+
+Copyright (c) 2026 Property Management Network. All rights reserved.
+
+This software and its source code (the "Software") are proprietary and
+confidential. The Software is licensed, not sold.
+
+No permission is granted to any person or entity to use, copy, reproduce,
+modify, merge, publish, distribute, sublicense, sell, or create derivative
+works of the Software, in whole or in part, by any means, without the prior
+express written consent of the copyright holder.
+
+Unauthorized copying, distribution, or use of the Software, via any medium,
+is strictly prohibited.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE, AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES, OR OTHER LIABILITY,
+WHETHER IN AN ACTION OF CONTRACT, TORT, OR OTHERWISE, ARISING FROM, OUT OF,
+OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.