Document NFT media runtime validation

[JOY (JOY)]

Description and Related Issue(s)

Updates the Vietnamese dark-theme NFT media report with the final production runtime evidence after the GCS integration and Erlang short-name fix were deployed.

Proposed Changes

• Record backend PRs mobil view for pages content blockscout/frontend#117, Up-chakra-version blockscout/frontend#119, and add 404 error for unknown networks blockscout/frontend#120.
• Record successful Mainnet and Testnet workflow run 30331379243.
• Update the observed Mainnet container creation timestamp.
• No environment variables are added or changed.

Breaking or Incompatible Changes

None. This PR changes documentation only.

Additional Information

The HTML report was served through a local HTTP server and validated in Chromium. It has a native dark color scheme, Vietnamese content, and no console errors.

Checklist for PR author

• I have tested these changes locally.
• I added tests to cover any new functionality, following this guide
• Whenever I fix a bug, I include a regression test to ensure that the bug does not reappear silently.
• If I have added a feature or functionality that is not privacy-compliant (e.g., tracking, analytics, third-party services), I have disabled it for private mode.
• If I have added, changed, renamed, or removed an environment variable
  • I updated the list of environment variables in the documentation
  • I made the necessary changes to the validator script according to the guide
  • I added "ENVs" label to this pull request

[gemini-code-assist]

Caution

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