Add Dependabot configuration for automated dependency updates

Configure Dependabot to automatically check for updates to:
- GitHub Actions (weekly)
- Docker base images (weekly)

This will help keep the repository's dependencies current and secure
by creating automated pull requests when updates are available.

🤖 Generated with Claude Code
https://claude.ai/code

Co-Authored-By: Claude <[email protected]>

Author: dguido

.github/dependabot.yml

@@ -0,0 +1,19 @@
+version: 2
+updates:
+  # Keep GitHub Actions up to date
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+    commit-message:
+      prefix: "ci"
+      include: "scope"
+  
+  # Keep Docker base images up to date
+  - package-ecosystem: "docker"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+    commit-message:
+      prefix: "docker"
+      include: "scope"