fix(ci): repin standards to a SHA that exists (5b1d0022 is nonexistent) (#60)

Pins `hyperpolymath/standards@5b1d00229e5e…`, which **does not exist**
(`gh api` → 422 "No commit found for SHA").

A workflow that cannot resolve its reusable dies at `startup_failure`
with **zero jobs** — no logs, no annotation. It therefore produces no
check runs, which is why required contexts such as `governance /
Validate Hypatia Baseline` register as *phantom* and block every PR in
the repo.

Repinned to `d5fe075a` (current `standards` main).

**Verified, not assumed:** hyperpolymath/hypatia#722 applied this same
fix and `governance / Validate Hypatia Baseline` went from absent to
**produced**; Mirror, Secret Scanner and Hypatia Scan went from
`startup_failure` to `success`.

**How it was caught:** `5b1d0022…0fbfedc7e80f37ea50f49236` and
`d135b05b…0fbfedc7e80f37ea50f49236` share a 24-character suffix — real
git SHAs don't collide like that. Of 27 distinct `standards` pins in
estate use, 26 resolve and this one does not.

Scope measured live: 27 references across 15 repos. `rsr-template-repo`
was fixed first (#41 there) as the RSR spine, since it propagates the
defect to every newly minted repository.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

Author: hyperpolymath

.github/workflows/mirror.yml

@@ -8,5 +8,5 @@ permissions:
   contents: read
 jobs:
   mirror:
-    uses: hyperpolymath/standards/.github/workflows/mirror-reusable.yml@5b1d00229e5e8c0c0fbfedc7e80f37ea50f49236
+    uses: hyperpolymath/standards/.github/workflows/mirror-reusable.yml@d5fe075a50ab3ce4f41614d66ed77f152fda134f
     secrets: inherit