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

cf-kv/wrangler.toml

@@ -0,0 +1,13 @@
+name = "excalidraw-worker"
+main = "index.js"
+compatibility_date = "2023-08-01"
+
+[durable_objects]
+bindings = [
+  { name = "CANVAS_OBJECT", class_name = "CanvasObject" },
+  { name = "INDEX_OBJECT", class_name = "IndexObject" }
+]
+
+[[migrations]]
+tag = "v1"
+new_sqlite_classes = ["CanvasObject", "IndexObject"]