Merge origin/main (v1.91.9.0, #2998) into capy/audit-fix-wave; release as v1.91.10.0

Main shipped v1.91.9.0, so this wave becomes v1.91.10.0. Conflicts kept this
branch's planner-derived assertions. Main's new test-value eval gets rule
kinds for its three gate cases and its measured 332 s duration from #2998's
CI; census counts and the PR fallback floor follow the new file. The packing
test now weighs each tier's recorded durations the way the planner does.

AGENTS.md

@@ -29,6 +29,7 @@ Invoke them by name (e.g., `/office-hours`).
 |-------|-------------|
 | `/review` | Pre-landing PR review. Finds bugs that pass CI but break in prod. |
 | `/deslop-shared-libs` | Find worthwhile shared-code extractions in recent work. Recommendations only. |
+| `/test-audit` | Sweep existing tests for low-value, implementation-coupled or duplicate tests. Report-only unless you approve a batch. |
 | `/codex` | Second opinion via OpenAI Codex. Review, challenge, or consult modes. Available outside the Codex harness. |
 | `/claude-code` | Second opinion via Claude Code. Review, challenge, or consult modes. Available outside the Claude Code harness. |
 | `/investigate` | Systematic root-cause debugging. No fixes without investigation. |