chore(docker): improve base image and organize docker files

- Add wget, ripgrep, python3, and GitHub CLI (gh) to base image
- Add OPENCODE_ALLOW_ALL_MODELS=true to production ENV
- Move compose files, onboard-smoke Dockerfile to docker/
- Move entrypoint script to scripts/docker-entrypoint.sh
- Add Podman Quadlet unit files (pod, app, db containers)
- Add docker/README.md with build, compose, and quadlet docs
- Add scripts/docker-build-test.sh for local build validation
- Update all doc references for new file locations
- Keep main Dockerfile at project root (no .dockerignore changes needed)

Co-Authored-By: Paperclip <noreply@paperclip.ing>

scripts/docker-onboard-smoke.sh

@@ -242,7 +242,7 @@ echo "==> Building onboard smoke image"
 docker build \
   --build-arg PAPERCLIPAI_VERSION="$PAPERCLIPAI_VERSION" \
   --build-arg HOST_UID="$HOST_UID" \
-  -f "$REPO_ROOT/Dockerfile.onboard-smoke" \
+  -f "$REPO_ROOT/docker/Dockerfile.onboard-smoke" \
   -t "$IMAGE_NAME" \
   "$REPO_ROOT"