Add Gitea CI/CD for hamkadr.ir (Nexus build + self-hosted compose deploy)

- .gitea/workflows/ci-cd.yml: dotnet build via mirror.soroushasadi.com; self-hosted deploy with pg_dump backup, rollback tag, scoped recreate, /healthz wait, prune
- Dockerfile (sdk/aspnet 10 via Nexus) + nuget.docker.config + .dockerignore
- docker-compose.prod.yml: app on 127.0.0.1:APP_PORT, Postgres internal-only + named volume
- deploy/nginx-hamkadr.ir.conf + DEPLOY.md (ports: 22/80/443 only; DB never exposed)
- Prod seeds reference data only (no demo listings); ForwardedHeaders for nginx TLS; /healthz endpoint

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

nuget.docker.config

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<configuration>
+  <packageSources>
+    <clear />
+    <add key="nexus"
+         value="https://mirror.soroushasadi.com/repository/nuget-group/index.json"
+         protocolVersion="3" />
+  </packageSources>
+  <config>
+    <add key="http_retry_count" value="8" />
+    <add key="http_retry_delay_milliseconds" value="1000" />
+  </config>
+</configuration>