Add GitHub Actions workflow for downloadable web build artifacts

[Copilot]

Automated web build generation with downloadable artifacts. Project remains on Flutter SDK >=2.16.1 (no dependency upgrades).

Changes

• Workflow (.github/workflows/web_build_artifact.yaml)

  • Triggers: push to master/main, manual dispatch
  • Outputs: ZIP archive + raw build directory
  • Retention: 90 days
  • Permissions: explicit contents: read

• Documentation

  • WEB_BUILD_DOWNLOAD.md: Download instructions, local serving (Python/Node/PHP), troubleshooting
  • README.md: Quick links to artifacts and docs
  • WEB_BUILD_SETUP_SUMMARY.md: DE/EN technical overview

Technical Notes

Base href set to / for straightforward local testing. Workflow requires one-time approval on PR branches (GitHub security feature), then runs automatically post-merge.

Artifacts available at: Actions → Web Build Artifact → [run] → Artifacts

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• canonical-lgw01.cdn.snapcraftcontent.com
  • Triggering command: /usr/lib/snapd/snapd /usr/lib/snapd/snapd (dns block)
• https://storage.googleapis.com/flutter_infra_release/flutter/3452d735bd38224ef2db85ca763d862d6326b17f/dart-sdk-linux-x64.zip
  • Triggering command: /usr/bin/curl curl --retry 3 --continue-at - --location --output /tmp/flutter/bin/cache/dart-sdk-linux-x64.zip REDACTED (http block)
• https://storage.googleapis.com/flutter_infra_release/releases/stable/linux/flutter_linux_3.19.6-stable.tar.xz
  • Triggering command: /usr/bin/curl curl -o flutter.tar.xz REDACTED (http block)
• https://storage.googleapis.com/flutter_infra_release/releases/stable/linux/flutter_linux_3.24.5-stable.tar.xz
  • Triggering command: /usr/bin/wget wget -q REDACTED -O flutter.tar.xz (http block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

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