[repo-assist] test SiteMappingService TOC generation

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🤖 This PR was created by Repo Assist, an automated AI assistant.

Summary

Add regression coverage for SiteMappingService.GetTocData, verifying deterministic chapter ordering, page ordering, and nested heading construction in the generated table of contents.

Rationale

The service’s hierarchy-building logic had no direct test. This focused test protects the ordering and nesting behavior used by the site navigation without changing production code or adding dependencies.

Test Status

• ✅ dotnet build EssentialCSharp.Web.Tests/EssentialCSharp.Web.Tests.csproj --configuration Release --no-restore
• ✅ git diff --check
• ⚠️ dotnet test EssentialCSharp.Web.Tests/EssentialCSharp.Web.Tests.csproj --configuration Release --no-build: 150/152 passed; CaptchaService_Verify_Success and KnownBreachedPassword_IsDetected require unavailable external services.

No new dependencies were added.

Warning

Firewall blocked 2 domains

The following domains were blocked by the firewall during workflow execution:

• api.hcaptcha.com
• api.pwnedpasswords.com

To allow these domains, add them to the network.allowed list in your workflow frontmatter:

network:
  allowed:
    - defaults
    - "api.hcaptcha.com"
    - "api.pwnedpasswords.com"

See Network Configuration for more information.

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