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/app/login/page.js

@@ -106,7 +106,7 @@ export default function LoginPage() {
               type="submit"
               variant="primary"
               className="w-full"
-              isLoading={loading}
+              loading={loading}
             >
               Login
             </Button>