Add Dependabot configuration for npm and GitHub Actions (#10)

Sets up weekly dependency update checks for both npm packages
and GitHub Actions workflows, with @callicles as reviewer.

https://claude.ai/code/session_015W86SJq7uqnADm78BJDQkn

Co-authored-by: user.email <noreply@anthropic.com>

Author: callicles

.github/dependabot.yml

@@ -0,0 +1,15 @@
+version: 2
+updates:
+  - package-ecosystem: "npm"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+    reviewers:
+      - "callicles"
+
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+    reviewers:
+      - "callicles"