fix(ci): drop the beta-Rust CodeQL leg, keep an actions leg

CodeQL Rust support is beta — that matrix leg cancels/hangs and never resolves
(the recurring "CodeQL checks 2 things forever" symptom), giving zero real
coverage. Removed it; ensured an actions leg remains so the matrix is non-empty
(no zero-jobs startup_failure). Rust security belongs in cargo-audit/clippy.

Verified with actionlint: no parse/syntax errors; actions leg present, no
active rust leg.

Part of the estate-wide CI cleanup (13 repos; reference hyperpolymath/gitbot-fleet#375).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: hyperpolymath

.github/workflows/codeql.yml

@@ -27,8 +27,6 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - language: rust
-            build-mode: none
           - language: actions
             build-mode: none
     steps: