Add µPaaS deployment setup for fsn1app1

- Add Docker HEALTHCHECK instruction probing /.well-known/healthcheck.json
  (30s interval, 5s timeout, 10s start period, 3 retries) for µPaaS
  container health verification
- Create deploy/README.md with full µPaaS app configuration reference
  (app name, repo URL, branch, env vars, volumes, ports, production config)
- Add Deployment section to README.md linking to deploy docs
- Add deploy/ to .dockerignore (docs not needed in build context)

Dockerfile

@@ -75,4 +75,7 @@ WORKDIR /var/lib/pixa
 
 EXPOSE 8080
 
+HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
+    CMD wget -q --spider http://localhost:8080/.well-known/healthcheck.json
+
 ENTRYPOINT ["/usr/local/bin/pixad", "--config", "/etc/pixa/config.yml"]