docs(integration): add Harbor registry integration guide

[majinghe]

Summary

Adds a Harbor guide under a new Registry category in the Integration section, in all five locales (en, zh, de, fr, ja), following the established integration guide structure. Harbor's GitHub repository is linked in the product introduction.

• Deploys RustFS with Docker Compose alongside goharbor/registry-photon — the registry component Harbor itself ships — configured with the distribution S3 storage driver pointed at the RustFS endpoint (regionendpoint: http://rustfs:9000, secure: false, skipverify: true, redirect.disable: true).
• Pushes an image, pulls it back after deleting the local copy, and verifies the docker/registry/v2/ objects (_layers, _manifests) through rc ls and a Console screenshot (light theme, ≤300 KB; Chinese capture in zh, English captures in the other locales).
• Maps the same settings to a full Harbor deployment: Helm chart persistence.imageChartStorage values and the storage_service.s3 keys behind harbor.yml.
• Adds the new Registry category landing pages and wires them into every locale's integration/meta.json and Integration overview (description + bullet), on top of the current Data Analytics / Observability / Others categories.

Verification

Validated end to end on Ubuntu 24.04 against goharbor/registry-photon:v2.12.2 and rustfs/rustfs-x86-musl:v2.3.1:

• curl http://localhost:5000/v2/_catalog → {"repositories":["demo/app"]}
• docker push localhost:5000/demo/app:v1 → blobs stored in RustFS under docker/registry/v2/ (12 objects, 2.1 MiB in the bucket)
• docker rmi + docker pull localhost:5000/demo/app:v1 → layers served from RustFS

npm run docs:check passes; npm run build passes (2595 pages); locale audit reports no findings for the new pages. Based on current main (includes #143, #148, #149).

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