Add authentication and assets

src/lang/Strings.ts

@@ -0,0 +1,11 @@
+export default class Strings {
+  public static randomString(length: number): string {
+    return Math.random()
+      .toString(36)
+      .substring(2, 2 + length);
+  }
+
+  private constructor() {
+    throw new Error('Strings is a static class that may not be instantiated');
+  }
+}

src/lang/assertUnreachable.ts

@@ -0,0 +1,3 @@
+export default function assertUnreachable(x: never): never {
+  throw new Error(`Error: Reached un-reachable code with [${x}]`);
+}