feat: add service catalog management with policy integration for domain-based resource access control

Add ServiceCatalogItem type and services CRUD API endpoints (list, create, update, delete). Extend Policy type to include services array with domain, upstream_ip, proxy_ip, and ports metadata.

Add ServicesPage component with table view and create/edit modals for managing service definitions. Include service name, domain, proxy, and upstream columns with port parsing logic.

Integrate service selection

deploy/access-proxy/Dockerfile

@@ -0,0 +1,10 @@
+FROM golang:1.23-alpine AS builder
+
+WORKDIR /src
+COPY access-proxy/ ./
+RUN go build -o /out/nexavpn-access-proxy ./main.go
+
+FROM alpine:3.21
+RUN apk add --no-cache ca-certificates
+COPY --from=builder /out/nexavpn-access-proxy /usr/local/bin/nexavpn-access-proxy
+ENTRYPOINT ["nexavpn-access-proxy"]