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/index.js

@@ -0,0 +1,16 @@
+var static = require("node-static");
+
+var file = new static.Server(".");
+PORT = 8080;
+
+console.info(`Running at http://localhost:${PORT}`);
+
+require("http")
+  .createServer(function (request, response) {
+    request
+      .addListener("end", function () {
+        file.serve(request, response);
+      })
+      .resume();
+  })
+  .listen(PORT);