[TASK] Define CODEOWNERS

Add .github/dependabot.yml to enable weekly Dependabot updates for GitHub Actions (limit 5 open PRs, apply "bot" label, and use commit prefix "[CHORE](deps)"). Add CODEOWNERS to set @OvertureMaps/omf-public-reviewers as the default owner for the repository. These changes automate dependency updates and establish default code ownership for reviews.

Author: lowlydba

.github/dependabot.yml

@@ -0,0 +1,15 @@
+---
+version: 2
+updates:
+
+  # Maintain GitHub Actions dependencies
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+    open-pull-requests-limit: 5
+    labels:
+      - "bot"
+    commit-message:
+      prefix: "[CHORE](deps)"
+      include: "scope"

CODEOWNERS

@@ -0,0 +1,2 @@
+# Default owners for everything in the repo
+* @overturemaps/omf-public-reviewers