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).

backend/src/routes/adminSystem.js

@@ -131,7 +131,7 @@ router.get('/updates/instructions', adminAuth, requirePermission('settings.view'
       channel: updateInfo.channel,
       environment: env,
       instructions,
-      releaseNotesUrl: `https://github.com/the-luap/picpeak/releases/tag/v${updateInfo.latest.forChannel}`
+      releaseNotesUrl: `https://github.com/PicPeak/picpeak/releases/tag/v${updateInfo.latest.forChannel}`
     });
   } catch (error) {
     logger.error('Error generating update instructions:', error);