Fix a bunch of errors we had

packages/backend/convex/globals.d.ts

@@ -0,0 +1,11 @@
+// Declare process.env for Convex backend environment variables.
+// Convex supports process.env to read variables set in the Convex Dashboard.
+declare const process: {
+  readonly env: {
+    readonly USESEND_API_KEY?: string;
+    readonly USESEND_URL?: string;
+    readonly USESEND_FROM_EMAIL?: string;
+    readonly CONVEX_CLOUD_URL?: string;
+    readonly [key: string]: string | undefined;
+  };
+};