Fix first: dont build the Dockerfile directly. Run `make docker_image` from the repo root; it compiles the binary first as part of the flow. Maintainer-confirmed.

```text
COPY zitadel /app/zitadel -> Zitadel folder not available
```

1. From the repo root, run `make docker_image`.
2. Expected: the binary is compiled, the COPY step finds it, and the image builds.

When to use: building Zitadel through build/dockerfile fails because the COPY zitadel step cannot find the binary.

When not to use: other Docker build failures (missing base images, network issues); those are different problems.

Compatibility: zitadel repo, build/dockerfile. Reported in zitadel/zitadel#6277.

Variants:
- "zitadel folder not available docker build"
- "COPY zitadel /app/zitadel fails"
- "zitadel make docker_image"

Root cause: the Dockerfile expects a prebuilt zitadel binary in the build context. Building the Dockerfile directly skips the compile step, so there is nothing to copy.

Edge cases: if make docker_image itself fails, fix the compile error first. The Dockerfile was never meant to be built standalone.