Add Harbor fallback for catalog and search endpoints

[pguinet]

Summary

• Harbor robot accounts are denied access to the V2 _catalog endpoint (scope registry:catalog:* returns an empty JWT), making catalog browsing and image search non-functional for Harbor registries
• This PR adds automatic Harbor detection and transparently falls back to the native Harbor project API (/api/v2.0/projects/{name}/repositories) for both catalog listing and image search
• No configuration change required — Harbor registries are detected automatically via the WWW-Authenticate header and /api/v2.0/ping, with a 5-minute cache

Changes

src/lib/server/docker.ts

• isHarborRegistry(): detect Harbor via WWW-Authenticate + /api/v2.0/ping (result cached 5 min)
• harborListRepositories(): list repos through Harbor project API with pagination support
• harborSearchRepositories(): search repos using Harbor's q=name=~{term} filter
• HarborCatalogResult type + getHarborBasicAuth() helper

src/routes/api/registry/catalog/+server.ts

• Harbor detection before _catalog call, delegates to handleHarborCatalog()

src/routes/api/registry/search/+server.ts

• Harbor detection in searchCatalog(), delegates to harborSearchRepositories()

Test plan

• Tested against a real Harbor instance with a robot account
• Catalog listing returns repositories correctly
• Image search returns filtered results
• Non-Harbor registries are unaffected (fallback is only triggered for Harbor)
• Built and deployed as fnsys/dockhand:harbor-fix

Fixes #360

🤖 Generated with Claude Code

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9 out of 10 committers have signed the CLA.

✅ sieren
✅ matt-boris
✅ FlintyLemming
✅ vikte
✅ shamoon
✅ TimElschner
✅ flohoss
✅ pguinet
✅ artbird309
❌ jotka
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[jotka]

hi @pguinet - we need all comments to be in english.

[pguinet]

Hello @jotka - Sorry about that! I've translated all comments to English in the latest commit. Won't happen again.

[jotka]

@pguinet can i ask you to sync your fork and rebase on main?

  git fetch upstream
  git rebase upstream/main
  git push --force

sorry for the force push.

[pguinet]

@jotka done — rebased on main and force-pushed. Branch is now up to date (2 commits: Harbor fallback + English comments translation).