ci: switch CodeQL matrix javascript-typescript -> actions (Hypatia-prescribed)

The repo has no JS/TS source, so `analyze (javascript-typescript, none)`
failed on every run with "no source files". Switch the CodeQL matrix to
`actions` (scans the GitHub Actions workflows every repo has), per Hypatia's
`switch_codeql_matrix_to_actions` recommendation. build-mode none is correct
for the actions language.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Mbq6yKF9RhFai6EQ7WqKhQ

Author: claude

.github/workflows/codeql.yml

@@ -30,7 +30,7 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - language: javascript-typescript
+          - language: actions
             build-mode: none
 
     steps: