Docs: append blocked frontier pilot marker

[cursor]

Summary

Append one line to docs/AUTOMATION_PILOT.md noting that the blocked frontier pilot ran second after the smoke ticket closed.

Related Issue

Closes #321

Solution module

• Runtime (DesignPatterns/)
• Diagnostics (DesignPatterns.Diagnostics/)
• SourceGenerators (DesignPatterns.SourceGenerators/)
• Analyzers (DesignPatterns.Analyzers/ + DesignPatterns.CodeFixes/)
• DependencyInjection (DesignPatterns.Extensions.DependencyInjection/)
• Package (DesignPatterns.Package/)
• Docs / Repository (README, docs/, .github/, AGENTS.md, build/)

Type of change

• Bug fix
• Feature
• Source generator / diagnostic / CodeFix change
• Refactor (no behavior change)
• Docs / repo metadata only

Test plan

• Verified append-only change to docs/AUTOMATION_PILOT.md (no other files)
• ./build.ps1 --target Ci --configuration Release (or CiPack if packaging changed) — not required for docs-only pilot
• Sibling samples (if API/generator behavior changed): clone DesignPatterns.Samples beside this repo and run ./build.ps1 --target Ci

Breaking changes

• None
• Yes — describe migration steps (APIs may still be pre-stable):

Checklist

• This PR touches only one solution module (see AGENTS.md)
• Commit messages are in English (no AI/agent tooling mentions in commits)
• PR description is English only — no AI/agent/Cursor tool attribution, no auto-generated summary blocks (e.g. CURSOR_SUMMARY, "Made with …")
• No version bumps, tags, releases, or NuGet publish steps included unless explicitly requested
• Public API / diagnostic / generated code changes are documented if user-visible

Documentation checklist

• Design Doc updated if API / diagnostic / implementation changed
• User-facing docs synced (separate PRs if multi-repo)
• No documentation changes needed