fix: regenerate REGISTRY.a2ml — stale RSR source_hash after #515 (#519)

`Registry Verify` has been failing on **`main`** since #515 merged at
~12:34 today.

#515 changed tracked files under `rhodium-standard-repositories/`
without regenerating the derived registry, so the RSR entry's
`source_hash` — a sha256 over `git ls-files -s <home>` — no longer
matches the tree:

```
DRIFT: .machine_readable/REGISTRY.a2ml is stale — run 'just registry'
```

**Every open PR inherits this**, because `pull_request` checks run
against the merge ref. It is the sole cause of the current red on #518.

## The change

One line, produced by `bash scripts/build-registry.sh` with no manual
editing:

```diff
 name = "RSR — Rhodium Standard Repositories"
 home = "rhodium-standard-repositories/"
-source_hash = "sha256:b285134b…7b9b7abe"
+source_hash = "sha256:02b75b57…c382f1e"
```

## Verified

| | `scripts/build-registry.sh --check` |
|---|---|
| `origin/main` | `DRIFT: .machine_readable/REGISTRY.a2ml is stale` |
| this commit | `OK: registry + topology are in sync with the file
tree.` (exit 0) |

Run history confirms the regression point — `main` green at 04:48, red
at 12:37, with `feat/scaffold-lifecycle-canon` red at 12:34.

Worth considering as follow-up: `just hooks-install` (the pre-commit
guard the failure message already points at) would have caught this
before push.

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

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

Author: hyperpolymath

.machine_readable/REGISTRY.a2ml

@@ -225,7 +225,7 @@ name = "RSR — Rhodium Standard Repositories"
 stream = "governance"
 home = "rhodium-standard-repositories/"
 canonical_doc = "rhodium-standard-repositories/README.adoc"
-source_hash = "sha256:b285134b201fdc899ca3cc483e7fdb5b5720fef02a56b07e5b1e8c537b9b7abe"
+source_hash = "sha256:02b75b57a41d213e4d3e7687e22252ba60bbef0923f75ebe18ef1a962c382f1e"
 route = "the repository-compliance standard every repo is graded against"
 
 [[spec]]