fix: convert cf-kv and excalidraw-libraries from submodules to regular files

- Remove stale cloudflare-worker submodule entry from .gitmodules
- Remove .git dirs from cf-kv and excalidraw-libraries so Git tracks them as regular files
- Fixes 'No url found for submodule path cf-kv' CI error

excalidraw-libraries/.github/dependabot.yml

@@ -0,0 +1,8 @@
+version: 2
+updates:
+  - package-ecosystem: npm
+    directory: /
+    schedule:
+      interval: weekly
+      day: sunday
+      time: "01:00"