chore: migrate Docker registry + GitHub URLs to PicPeak org

Repo transferred from the-luap/picpeak → PicPeak/picpeak. Docker images
publish to ghcr.io/picpeak/picpeak/{backend,frontend} (lowercase, per the
GHCR canonical form computed by docker-build.yml's `${GITHUB_REPOSITORY,,}`).

Sweep covers:
- docker-compose.production.yml + Dockerfiles → new image registry path
- README, CONTRIBUTING, SECURITY, SIMPLE_SETUP, scripts/picpeak-setup.sh
  → new GitHub URLs
- Update-check / release-notes services (updateCheckService,
  environmentService, updateNotificationService, adminSystem,
  UpdateNotification, githubReleaseUrl) → GitHub API + tag URLs use the
  canonical PicPeak/picpeak path
- Issue templates + README-DOCKER + workflow README → updated package URLs
- One commit-context comment in migrations/090 + customerAccountsService

CHANGELOG.md is intentionally untouched (historical release entries are
immutable; GitHub auto-redirects the old URLs indefinitely).
CLAUDE.md keeps the bare `(the-luap)` reference — that's the maintainer's
personal handle, not a repo URL.

22 files, 48/48 line swaps (every change is a 1:1 URL replacement).

frontend/Dockerfile

@@ -8,7 +8,7 @@ ARG VCS_REF
 ARG VERSION
 
 # Add labels for GitHub Container Registry
-LABEL org.opencontainers.image.source="https://github.com/the-luap/picpeak"
+LABEL org.opencontainers.image.source="https://github.com/PicPeak/picpeak"
 LABEL org.opencontainers.image.description="PicPeak Frontend Application"
 LABEL org.opencontainers.image.licenses="MIT"