Add Docker Hub sync workflow and README files for fileserver, gitweb, and wechat

[touero]

Motivation

• Keep Docker Hub repository descriptions and full overviews in sync with repository README.md content for the container images.
• Provide basic documentation for the three image projects fileserver, gitweb, and wechat so the workflow can extract meaningful summaries.
• Allow an optional Docker Hub category to be applied to all repos via workflow input.

Description

• Add a GitHub Actions workflow /.github/workflows/sync-dockerhub-repo-info.yml that logs into the Docker Hub API, extracts a short description and full description from each repo README.md, and PATCHes the Docker Hub repository metadata using curl and jq.
• The workflow installs jq, obtains a JWT from Docker Hub using curl, trims the short description to 100 bytes while preserving UTF-8 via an inline python3 snippet, and supports an optional category input applied to all repos.
• The workflow iterates a hardcoded repo list fileserver, gitweb, and wechat, validates each README.md exists, and fails the job with diagnostic output on HTTP or other failures.
• Add new README.md files for fileserver, gitweb, and wechat with highlights and basic docker run usage examples.

Testing

• No automated tests were executed as part of this change and the workflow has not been run in CI yet.
• The workflow steps use standard tools (curl, jq, python3, awk) and include HTTP status checks to surface failures during execution.
• The new README.md files were added as static documentation and require no runtime tests.

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Codex Task

[touero]

@copilot resolve the merge conflicts in this pull request