Add cooldown and groups to dependabot config

- Change interval from daily to weekly for both ecosystems
- Add 7-day cooldown to github-actions ecosystem
- Add groups configuration to batch updates
- Fix missing newline at EOF

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: dguido

.github/dependabot.yml

@@ -4,10 +4,18 @@ updates:
   - package-ecosystem: github-actions
     directory: /
     schedule:
-      interval: daily
+      interval: weekly
+    cooldown:
+      default-days: 7
+    groups:
+      all:
+        patterns: ["*"]
   - package-ecosystem: uv
     directory: /
     schedule:
-      interval: daily
+      interval: weekly
     cooldown:
-      default-days: 7
+      default-days: 7
+    groups:
+      all:
+        patterns: ["*"]