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).

docker-compose.production.yml

@@ -45,7 +45,7 @@ services:
   backend:
     # Use pre-built image from GitHub Container Registry
     # PICPEAK_CHANNEL: 'stable' (default), 'beta', or specific version like 'v2.3.0'
-    image: ghcr.io/the-luap/picpeak/backend:${PICPEAK_CHANNEL:-stable}
+    image: ghcr.io/picpeak/picpeak/backend:${PICPEAK_CHANNEL:-stable}
     container_name: picpeak-backend
     env_file: .env
     environment:
@@ -93,7 +93,7 @@ services:
   frontend:
     # Use pre-built image from GitHub Container Registry
     # Uses same channel as backend for consistency
-    image: ghcr.io/the-luap/picpeak/frontend:${PICPEAK_CHANNEL:-stable}
+    image: ghcr.io/picpeak/picpeak/frontend:${PICPEAK_CHANNEL:-stable}
     container_name: picpeak-frontend
     # Note: Pre-built frontend uses Nginx to proxy /api to backend:3001.
     # Prefer keeping API base as '/api' in builds to avoid CORS.