fix(ci): add .yamllint.yml to fix failing lint-yaml job

[Copilot]

squad-standard-lint-yaml.yml runs yamllint -s $files with no -c flag, so it falls back to yamllint's built-in defaults (80-char line limit). Several workflow files have lines exceeding that limit (dotnet CLI commands, shell scripts), causing [line-length] errors and a non-zero exit.

Changes

• Added .yamllint.yml at repo root — yamllint auto-discovers this when run without -c
  • line-length: max: 200 — matches the inline config already used in lint-yaml.yml
  • document-start: disable — GitHub Actions workflows omit ---
  • truthy: allowed-values: ['true', 'false', 'on'] — on: is standard in GHA
  • comments: min-spaces-from-content: 1 — pre-existing files use single-space before inline comments
  • brackets spacing — consistent with lint-yaml.yml
  • ignore: .squad/ — excludes squad orchestration files

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ Feature (non-breaking change that adds functionality)
• ♻️ Refactor (no behavior change, code cleanup/restructure)
• 🧪 Tests (new or updated tests only)
• 📝 Docs (README, XML docs, comments)
• ⚙️ Infra/CI (GitHub Actions, Aspire, NuGet, deployment)
• 🔒 Security (auth, permissions, secrets, headers)
• 💥 Breaking change (existing behavior changes)

Domain Affected

• 🏗️ Architecture / domain logic / CQRS → Aragorn required
• 🔧 Backend (handlers, repositories, API endpoints, MediatR) → Sam required
• ⚛️ Frontend (Blazor components, Razor pages, CSS, JS) → Legolas required
• 🧪 Unit / bUnit / integration tests → Gimli required
• 🧪 E2E / Playwright / Aspire integration tests → Pippin required
• ⚙️ CI/CD / GitHub Actions / NuGet / Aspire AppHost → Boromir required
• 🔒 Auth0 / authorization / security-relevant changes → Gandalf required
• 📝 Docs / README / XML docs → Frodo required

Self-Review Checklist

Code Quality

• I ran dotnet build MyBlog.slnx --configuration Release — 0 errors, 0 warnings
• I ran dotnet test MyBlog.slnx --configuration Release --no-build — all pass
• No TODO/FIXME left unless tracked in a follow-up issue (link it)
• No secrets, API keys, or credentials committed

Architecture

• New handlers follow the Command/Query/Handler/Validator naming conventions
• New handlers are sealed
• Domain layer has no references to Web or Persistence.* projects
• Result<T> / ResultErrorCode used for expected failures (no exception-driven control flow)
• DTOs are records in Domain.DTOs; Models are in Domain.Models
• No DTO types embedded in Model classes

Tests

• New code has corresponding unit tests
• Integration tests use domain-specific collections ([Collection("XxxIntegration")])
• No test compares two IssueDto.Empty / CommentDto.Empty instances directly

Security (check if security-relevant)

• New endpoints have appropriate RequireAuthorization / policy applied
• No MarkupString used with user-supplied content
• No user input reflected in MongoDB queries without sanitization

Merge Readiness

• Branch is up to date with main (no merge conflicts)
• CI checks are green (do not request review while checks are pending/failing)
• PR description is complete — reviewers should not have to ask what this does

Screenshots / Evidence

yamllint -s $(git ls-files '*.yml' '*.yaml' | tr '\n' ' ') exits 0 locally with the new config in place. Previously failed with exit code 1 on [line-length] errors in squad-insider-release.yml, squad-milestone-release.yml, squad-promote.yml, squad-release.yml, and squad-standard-lint-markdown.yml.

Notes for Reviewers

The new .yamllint.yml is now the single source of truth for YAML lint rules across both lint-yaml.yml (uses ibiqlik/action-yamllint with inline config_data — unaffected) and squad-standard-lint-yaml.yml (now inherits from the file). The two configs were previously divergent; this brings them into alignment.

[github-actions]

🏗️ PR Added to Squad Triage Queue

This PR has been labeled with squad and added to the triage queue.

Next steps:

• The squad Lead will review and assign to an appropriate team member
• A squad:member label will be added after triage

If you know which squad member should handle this, you can add the appropriate squad:member label yourself.

[github-actions]

Test Results Summary

556 tests  ±0   518 ✅ ±0   13s ⏱️ -1s
  6 suites ±0    38 💤 ±0 
  6 files   ±0     0 ❌ ±0 

Results for commit 27cc15c. ± Comparison against base commit 881a571.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.73%. Comparing base (881a571) to head (27cc15c).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #447   +/-   ##
=======================================
  Coverage   76.73%   76.73%           
=======================================
  Files          71       71           
  Lines        1775     1775           
  Branches      214      214           
=======================================
  Hits         1362     1362           
  Misses        336      336           
  Partials       77       77           

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• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
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[Copilot]

Pull request overview

This PR fixes the failing squad-standard-lint-yaml.yml job by adding a repo-root .yamllint.yml so yamllint (invoked without -c) uses consistent, project-appropriate rules instead of strict built-in defaults (notably the 80-character line-length rule).

Changes:

• Added a root .yamllint.yml that yamllint auto-discovers when no -c flag is provided.
• Relaxed line-length to max: 200 (matching the existing inline config used by .github/workflows/lint-yaml.yml).
• Tuned rules for GitHub Actions YAML patterns (truthy allowing on, disable document-start) and ignored .squad/ YAML files.