feat(vendor): warn when vendoring from an archived GitHub repository

[Copilot]

• Add logger concurrency guard test (Warn + concurrent SetOutput) in pkg/logger/atmos_logger_test.go
• Fix env-var docs phrasing in website/docs/cli/environment-variables.mdx (remove os.Setenv note)
• Add ATMOS_GITHUB_ARCHIVED_CHECK_TIMEOUT env-var section to website/docs/cli/configuration/vendor.mdx
• Add TODO comments above warnIfArchivedGitHubRepo calls in internal/exec/vendor_utils.go and internal/exec/vendor_component_utils.go
• Replace fmt.Sprintf("%s/%s", owner, repo) with owner + "/" + repo in vendor_github_archive.go (removed fmt import)
• Rename github import alias to ghclient in pkg/github/repo_test.go
• Update CHANGELOG.md with blog/docs links under Breaking Changes
• go test -race ./pkg/logger/... ./pkg/github/... — all pass, no data races

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Warn when vendoring from an archived repo</issue_title>
<issue_description>### Describe the Feature

Warn when vendoring from an archived repo

Expected Behavior

warning shown

Use Case

When vendoring

Describe Ideal Solution

See above

Alternatives Considered

No response

Additional Context

No response</issue_description>

<agent_instructions>Use the PR template. Use semantic commits. Think deeply. Use a semantic PR title.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes Warn when vendoring from an archived repo #2046

---

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[github-actions]

Warning

Release Documentation Required

This PR is labeled minor or major and requires documentation updates:

• Changelog entry - Add a blog post in website/blog/YYYY-MM-DD-feature-name.mdx
• Roadmap update - Update website/src/data/roadmap.js with the new milestone

Alternatively: If this change doesn't require release documentation, remove the minor or major label.

[github-actions]

Warning

Release Documentation Required

This PR is labeled minor or major and requires documentation updates:

• Changelog entry - Add a blog post in website/blog/YYYY-MM-DD-feature-name.mdx
• Roadmap update - Update website/src/data/roadmap.js with the new milestone

Alternatively: If this change doesn't require release documentation, remove the minor or major label.

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues found.

Snapshot Warnings

⚠️: No snapshots were found for the head SHA 46ece28.

Ensure that dependencies are being submitted on PR branches and consider enabling retry-on-snapshot-warnings. See the documentation for more information and troubleshooting advice.

Scanned Files

None

[codecov]

Codecov Report

❌ Patch coverage is 89.30818% with 17 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.22%. Comparing base (01541b6) to head (46ece28).

Files with missing lines	Patch %	Lines
pkg/github/repo.go	83.16%	13 Missing and 4 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2175      +/-   ##
==========================================
+ Coverage   77.18%   77.22%   +0.03%     
==========================================
  Files        1014     1016       +2     
  Lines       95883    96036     +153     
==========================================
+ Hits        74010    74166     +156     
+ Misses      17688    17686       -2     
+ Partials     4185     4184       -1     

Flag	Coverage Δ
unittests	77.22% <89.30%> (+0.03%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
internal/exec/vendor_component_utils.go	32.30% <100.00%> (+0.52%)	⬆️
internal/exec/vendor_github_archive.go	100.00% <100.00%> (ø)
internal/exec/vendor_utils.go	70.39% <100.00%> (+0.19%)	⬆️
pkg/logger/atmos_logger.go	95.65% <100.00%> (+1.28%)	⬆️
pkg/logger/global.go	83.33% <100.00%> (ø)
pkg/logger/log.go	92.50% <100.00%> (+0.19%)	⬆️
pkg/github/repo.go	83.16% <83.16%> (ø)

... and 5 files with indirect coverage changes

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[mergify]

💥 This pull request now has conflicts. Could you fix it @Copilot? 🙏