build: align Dockerfile with packer build and add docker-compose dev mounts

- Rebase Dockerfile onto almalinux9-base, install via uv tool install
- Remove dev artifacts (remotes.yaml, ca-bundle.pem) from image
- Mount gitignored dev files via docker-compose volumes instead
- Add .dockerignore to keep secrets out of build context
- Add pre-commit hook to validate docker build on Dockerfile changes
- Track docker-compose.yml in git (no secrets; dev files mounted as volumes)

.woodpecker/pre-commit.yaml

@@ -4,6 +4,8 @@ when:
 steps:
   - name: pre-commit
     image: git.unkin.net/unkin/almalinux9-base:20260308
+    environment:
+      BUILDAH_STORAGE_DRIVER: vfs
     commands:
       - dnf install -y buildah
       - uvx pre-commit run --all-files