ci: add concurrency groups to cancel redundant workflow runs

[thomhurst]

Summary

• Adds concurrency groups with cancel-in-progress: true to 7 GitHub Actions workflows that use push/pull_request triggers
• When a new commit is pushed to a PR branch, any in-progress run for that branch is automatically cancelled, saving runner time
• Uses github.head_ref || github.run_id so PR runs are grouped by branch while push/schedule/dispatch runs remain independent

Workflows updated

• .NET (dotnet.yml)
• Locale Test (dotnet-build-different-locale.yml)
• CloudShop Example Tests (cloudshop-example.yml)
• CodeQL Advanced (codeql.yml)
• Deploy to GitHub Pages (deploy-pages.yml)
• Test Deploy to GitHub Pages (deploy-pages-test.yml)
• Claude Code Review (claude-code-review.yml)

Skipped (no benefit)

• mock-benchmarks.yml — already has concurrency configured
• Schedule/event-only workflows (speed-comparison, claude-autofix, review-stale, claude-issue-triage, claude)

Test plan

• Verify workflow YAML is valid (CI will validate on this PR)
• Push a follow-up commit to this PR to confirm the first run gets cancelled

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

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