feat/sec add github's dependabot to scan the lib sec.

.github/dependabot.yml

@@ -0,0 +1,27 @@
+version: 2
+
+updates:
+
+  # Go dependencies (entire repo)
+  - package-ecosystem: "gomod"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+    labels:
+      - "dependencies"
+      - "go"
+
+  # Frontend dependencies
+  - package-ecosystem: "npm"
+    directory: "/web/frontend"
+    schedule:
+      interval: "weekly"
+    labels:
+      - "dependencies"
+      - "frontend"
+
+  # GitHub Actions
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "weekly"