Update mirror.gcr.io/library/ubuntu Docker tag to v26

[renovate-bot]

This PR contains the following updates:

Package	Type	Update	Change
mirror.gcr.io/library/ubuntu (source)	final	major	24.04 → 26.04

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[gemini-code-assist]

Code Review

This pull request attempts to upgrade the base Docker image from Ubuntu 24.04 to Ubuntu 26.04. However, feedback indicates that this upgrade is premature and will break the build because third-party repositories (such as Docker's) do not yet support the Ubuntu 26.04 codename, leading to 404 errors during package updates. It is recommended to revert back to Ubuntu 24.04.

[gemini-code-assist]

Upgrading the base image to Ubuntu 26.04 is premature and will break the Dockerfile build.

Specifically, the Docker repository setup on lines 76-79 uses $(lsb_release -cs) to fetch the Ubuntu codename:

RUN add-apt-repository \
  "deb [arch=amd64] https://download.docker.com/linux/ubuntu \
  $(lsb_release -cs) \
  stable"

Since Ubuntu 26.04 is not yet fully released or supported by third-party package repositories like Docker, the repository URL for this codename will return a 404 error during apt-get update on line 81.

Please keep the base image at ubuntu:24.04 until 26.04 is officially released and supported by all external dependencies configured in this Dockerfile.

FROM mirror.gcr.io/library/ubuntu:24.04