chore: standardize enterprise Dependabot configuration (#15)

* ci: add dependabot config with npm and github-actions

* ci: add CodeQL (JS/TS, excludes PHP) with workflow_dispatch

* chore: standardize enterprise Dependabot configuration

* chore: keep Dependabot PR focused

Author: somethingwithproof

.github/dependabot.yml

@@ -0,0 +1,12 @@
+version: 2
+updates:
+  - package-ecosystem: github-actions
+    directory: /
+    target-branch: main
+    schedule: {interval: weekly, day: friday}
+    open-pull-requests-limit: 5
+    cooldown: {default-days: 7}
+    groups:
+      github-actions: {patterns: ["*"]}
+    labels: [dependencies, github-actions]
+    commit-message: {prefix: ci, include: scope}