feat: OpenAI compatibility improvements & build fixes

- Fix hydration mismatches and initialization errors
- Add /v1/models endpoint for OpenAI clients
- Add Codex response translator (Responses → OpenAI)
- Fix circular dependencies and PropTypes
- Add Material Symbols font and CSS fixes
- Update README with deployment guide

Co-merged from PR #18 (14/15 commits, skipped debug)

src/shared/components/layouts/AuthLayout.js

@@ -1,6 +1,6 @@
 "use client";
 
-import { ThemeToggle } from "@/shared/components";
+import ThemeToggle from "../ThemeToggle";
 
 export default function AuthLayout({ children }) {
   return (