test: verify Docker image builds and starts successfully

[icebear0828]

This commit updates the GitHub Action workflow ci-docker.yml to utilize a matrix strategy to smoke test the Docker image over both port 8080 (default) and 8090 (custom override via env var PORT).
Additionally, it enhances docker-healthcheck.sh to correctly check for configurations overridden in environment variable PORT, /app/data/local.yaml, or /app/config/default.yaml securely before defaulting to 8080.

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PR created automatically by Jules for task 9278626766797036186 started by @icebear0828

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