Raise report upload request size limits

- Configure NestJS with an explicit JSON and urlencoded body parser limit controlled by API_BODY_LIMIT.

- Set the default API body limit to 100mb for report HTML, key frames, template images, and Data URL file uploads.

- Add a matching Nginx client_max_body_size 100m limit so Docker web proxy no longer rejects large report saves first.

- Document the new request body limit in README, deployment docs, progress notes, environment example, and AGENTS context.

- Rebuild and verify Docker web/api with a large report save through the Nginx /api proxy.

.env.example

@@ -1,5 +1,6 @@
 # Backend API development defaults.
 API_PORT=3100
+API_BODY_LIMIT="100mb"
 CORS_ORIGIN="http://localhost:3001,http://localhost:4002"
 DATABASE_URL="postgresql://surclaw:surclaw_dev_password@localhost:5433/surclaw?schema=public"
 SESSION_SECRET="change-me-in-production"