ci(codeql): cron weekly→monthly (cut 3, standards#288) (#40)

Per `standards#286` canonical (cut 3, Option B 2026-05-30): convert
CodeQL scheduled run from weekly `0 6 * * 1` to monthly `0 6 1 * *`.
PR-trigger runs unchanged — every PR still gets CodeQL.

Refs `hyperpolymath/standards#288` (campaign).

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## Summary

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## Changes

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-

## RSR Quality Checklist

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### Required

- [ ] Tests pass (`just test` or equivalent)
- [ ] Code is formatted (`just fmt` or equivalent)
- [ ] Linter is clean (no new warnings or errors)
- [ ] No banned language patterns (no TypeScript, no npm/bun, no
Go/Python)
- [ ] No `unsafe` blocks without `// SAFETY:` comments
- [ ] No banned functions (`believe_me`, `unsafeCoerce`, `Obj.magic`,
`Admitted`, `sorry`)
- [ ] SPDX license headers present on all new/modified source files
- [ ] No secrets, credentials, or `.env` files included

### As Applicable

- [ ] `.machine_readable/STATE.a2ml` updated (if project state changed)
- [ ] `.machine_readable/ECOSYSTEM.a2ml` updated (if integrations
changed)
- [ ] `.machine_readable/META.a2ml` updated (if architectural decisions
changed)
- [ ] Documentation updated for user-facing changes
- [ ] `TOPOLOGY.md` updated (if architecture changed)
- [ ] `CHANGELOG` or release notes updated
- [ ] New dependencies reviewed for license compatibility (MPL-2.0 /
MPL-2.0)
- [ ] ABI/FFI changes validated (`src/interface/abi/` and
`src/interface/ffi/` consistent)

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Author: hyperpolymath

.github/workflows/codeql.yml

@@ -7,7 +7,8 @@ on:
   pull_request:
     branches: [main, master]
   schedule:
-    - cron: '0 6 * * 1'
+    - cron: '0 6 1 * *'   # monthly 1st 06:00 UTC
+
 # Estate guardrail: cancel superseded runs so re-pushes / rebased PR
 # updates do not pile up queued runs against the shared account-wide
 # Actions concurrency pool. Applied only to read-only check workflows