Publishes container images to both registries:
- GHCR: ghcr.io/host-uk/core-images:{image} (org access)
- Docker Hub: lthn/{image}:{version} (public distribution)

Changes:
- Add Docker Hub login step (requires DOCKERHUB_USERNAME, DOCKERHUB_TOKEN secrets)
- Update metadata to generate tags for both registries
- Enable dev branch builds
- Fix LinuxKit build to use linuxkit directly (not core CLI)
- Use correct double-dash flags for linuxkit

Naming:
- developer -> ghcr.io/host-uk/core-images:developer + lthn/core-dev:latest
- server-php -> ghcr.io/host-uk/core-images:server-php + lthn/server-php:latest

Closes #1

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

server-php:
- Add nginx.conf, fpm-pool.conf.template, supervisord.conf
- Add php.ini.template, php-prod.ini, php-dev.ini
- Add opcache-prod.ini, xdebug.ini
- Add nginx-performance.conf for production
- Add entrypoint.sh script

developer:
- Remove git-delta (not available in Alpine 3.22 repos)

Closes #3

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

The builder stage copies patch/ to allow overriding vendor files.
For the base image this is empty with a README explaining usage.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

The Dockerfile requires product/ directory for the builder stage.
For the base image, this is a minimal placeholder that returns JSON.
Applications should mount their own code at /var/www/html.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

- Use separate image repos (ghcr.io/host-uk/core-dev, server-php)
- Trigger on dev branch instead of main
- Only build LinuxKit on tags
- Add fail-fast: false to continue if one image fails

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

- Dev branch: GHCR only (ghcr.io/host-uk/*)
- Main branch + tags: GHCR + Docker Hub (lthn/*)
- Requires DOCKERHUB_USERNAME and DOCKERHUB_TOKEN secrets

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

phpdocumentor/phpdocumentor doesn't support PHP 8.4 yet, causing
the composer global require to fail during image build.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Composer blocks plugins by default for security. Need to explicitly
allow pest-plugin before running composer global require.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

gopls@latest requires Go 1.25, scc/v3@latest requires Go 1.25.2.
Pin to known-working versions for Alpine's Go 1.24.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Several Go tools require newer Go versions than Alpine 3.22 provides.
Add || true to all go install commands to allow build to continue
if individual tools fail.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

- Terraform: install from HashiCorp binary (not in Alpine 3.22)
- lazydocker, ctop, mkcert, dasel, sops, trivy, trufflehog, k6:
  pin to specific versions with correct URL patterns
- All binary downloads now optional with || true fallback

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

- Add Python 3.13 via multi-stage build from official Alpine image
- Pin Claude Code CLI to version 2.1.29
- Update image description to reflect all four languages

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

- PHP 8.5.3 (was 8.4 on Alpine — Codex sandbox was failing)
- Debian Trixie base (Alpine stays for server-php/Blesta only)
- Multi-stage scratch exports: php, golang, node, python stages
  can be COPY --from'd independently by downstream images
- All PHP extensions clean: sockets, pcntl, sodium, opcache,
  imagick, xsl, redis, gd, intl, bcmath
- Go 1.26.1, Node 22, Python 3.13, Composer 2.9
- Image size: 2.9GB (was 6GB on Alpine)
- FrankenPHP static binary included

Co-Authored-By: Virgil <virgil@lethean.io>