Convert htmx-redirect-toast.js to TS; remove dead legacy utils.js (issue #17)

- Add ts/htmx-redirect-toast.ts: typed port of the hx-redirect-toast htmx
  extension. Stays a classic (non-module) script — only touches the global
  htmx and registers an extension; layout.py now serves dist/htmx-redirect-toast.js
- Delete games/static/js/utils.js: the legacy hand-written copy is dead — every
  compiled module imports dist/utils.js (from ts/utils.ts); nothing references
  the old path

With this, the only first-party JS served is compiled from ts/; the sole
remaining hand-written .js in static is the vendored datepicker.umd.js bundle.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

common/layout.py

@@ -337,7 +337,7 @@ def Page(
         "            htmx.config.scrollBehavior = 'smooth';\n"
         "            htmx.config.selfRequestsOnly = false;\n"
         "        </script>\n"
-        f'        <script src="{static("js/htmx-redirect-toast.js")}"></script>\n'
+        f'        <script src="{static("js/dist/htmx-redirect-toast.js")}"></script>\n'
         f"        {django_htmx_script(nonce=None)}\n"
         f'        <link rel="stylesheet" href="{static("base.css")}" />\n'
         # Vendored bundles (flowbite 2.4.1, alpinejs/@alpinejs/mask 3.15.12) —