docs(archive): Preserve discussion for PR #5471

[AceHack]

Automated archival of PR #5471.

[chatgpt-codex-connector]

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[Copilot]

Pull request overview

Archives and preserves the GitHub discussion/review content for PR #5471 under docs/pr-discussions/, keeping a git-native record of PR metadata plus review threads.

Changes:

• Added a new PR discussion archive markdown file for PR #5471 (frontmatter + preserved PR description and review threads).

[AceHack]

Both threads: no-op resolve.

Thread on line 52 (file-count): The "4 out of 4 changed files" text is Copilot's own self-reported review summary from the original PR #5471, faithfully preserved verbatim per .claude/rules/substrate-or-it-didnt-happen.md verbatim-preservation discipline. If the original count was inaccurate, that discrepancy was in Copilot's original review, not in the archive — and per the same rule we don't retroactively rewrite verbatim preservations.

Thread on line 58 (double-pipe): Per .claude/rules/blocked-green-ci-investigate-threads.md known FP class. Direct awk inspection of lines 56-57 (the actual table rows) confirms single | rows, not ||. Line 58 is blank (section break).