chore(394,395): record promoted potential entries for PR #391 follow-ups

[drmoisan]

Summary

• Records the promoted potential-entry artifacts for two follow-up findings identified during PR (chore): update packages #391 verification.
• Adds docs/features/potential/promoted/2026-07-20-utilitiescs-test-cs2002-duplicate-compile-entry.md, the promotion record behind issue Bug: utilitiescs-test-cs2002-duplicate-compile-entry #394 (CS2002 duplicate <Compile> entry in UtilitiesCS.Test.csproj).
• Adds docs/features/potential/promoted/2026-07-20-system-reactive-7-packages-config-migration.md, the promotion record behind issue Refactor: system-reactive-7-packages-config-migration #395 (System.Reactive 7.0 packages.config incompatibility warning).
• Documentation-only change; no production code, tests, or build configuration are modified.

Why

The feature-promotion lifecycle requires each potential entry promoted to a GitHub issue to have its promotion record committed under docs/features/potential/promoted/. Both entries were promoted via the drm-copilot promotion tooling on 2026-07-20; this PR lands the resulting artifacts so the repository audit trail matches the open issues. Direct pushes to main are blocked by repository rules, so the artifacts are delivered through this pull request.

What Changed

• Docs/templates: two new promotion-record Markdown files under docs/features/potential/promoted/ (+105 lines total, no deletions).

Architecture / How It Fits Together

Not applicable; no runtime components are affected. The files are inputs to the feature-promotion lifecycle (potential entry → issue → active feature folder) and will be referenced when issues #394 and #395 are picked up.

Verification

• Completed: PR context collected against origin/main (merge base 793508e7); changed-files overview confirms a docs-only diff of the two listed files.
• Recommended: none beyond CI; the change contains no executable content.

Backward Compatibility / Migration Notes

None. Additive documentation only.

Risks and Mitigations

• Risk: negligible; docs-only. Rollback is a single revert of this commit.

Review Guide

1. docs/features/potential/promoted/2026-07-20-utilitiescs-test-cs2002-duplicate-compile-entry.md — bug promotion record for issue Bug: utilitiescs-test-cs2002-duplicate-compile-entry #394.
2. docs/features/potential/promoted/2026-07-20-system-reactive-7-packages-config-migration.md — refactor promotion record for issue Refactor: system-reactive-7-packages-config-migration #395.

Follow-ups

• Issue Bug: utilitiescs-test-cs2002-duplicate-compile-entry #394: remove the duplicate <Compile> item in UtilitiesCS.Test.csproj.
• Issue Refactor: system-reactive-7-packages-config-migration #395: decide between PackageReference migration, a 6.x pin, or the documented escape hatch for System.Reactive 7.0.

GitHub Auto-close

• None