fix(auth): unify OAuth button styles and disable email login (#456)

All three OAuth CTAs (Google, GitHub, Twitter) now share a consistent
white pill-button style with light border instead of individual brand
colors. Email login section commented out as the backend flow is not
yet implemented.

app/src/components/oauth/providerConfigs.tsx

@@ -26,13 +26,13 @@ const GoogleIcon = ({ className = '' }: { className?: string }) => (
 );
 
 const TwitterIcon = ({ className = '' }: { className?: string }) => (
-  <svg className={className} viewBox="0 0 24 24" fill="#fff">
+  <svg className={className} viewBox="0 0 24 24" fill="#000">
     <path d="M18.244 2.25h3.308l-7.227 8.26 8.502 11.24H16.17l-5.214-6.817L4.99 21.75H1.68l7.73-8.835L1.254 2.25H8.08l4.713 6.231zm-1.161 17.52h1.833L7.084 4.126H5.117z" />
   </svg>
 );
 
 const GitHubIcon = ({ className = '' }: { className?: string }) => (
-  <svg className={className} viewBox="0 0 24 24" fill="#fff">
+  <svg className={className} viewBox="0 0 24 24" fill="#24292f">
     <path d="M12 0c-6.626 0-12 5.373-12 12 0 5.302 3.438 9.8 8.207 11.387.599.111.793-.261.793-.577v-2.234c-3.338.726-4.033-1.416-4.033-1.416-.546-1.387-1.333-1.756-1.333-1.756-1.089-.745.083-.729.083-.729 1.205.084 1.839 1.237 1.839 1.237 1.07 1.834 2.807 1.304 3.492.997.107-.775.418-1.305.762-1.604-2.665-.305-5.467-1.334-5.467-5.931 0-1.311.469-2.381 1.236-3.221-.124-.303-.535-1.524.117-3.176 0 0 1.008-.322 3.301 1.23.957-.266 1.983-.399 3.003-.404 1.02.005 2.047.138 3.006.404 2.291-1.552 3.297-1.23 3.297-1.23.653 1.653.242 2.874.118 3.176.77.84 1.235 1.911 1.235 3.221 0 4.609-2.807 5.624-5.479 5.921.43.372.823 1.102.823 2.222v3.293c0 .319.192.694.801.576 4.765-1.589 8.199-6.086 8.199-11.386 0-6.627-5.373-12-12-12z" />
   </svg>
 );
@@ -56,17 +56,17 @@ export const oauthProviderConfigs: OAuthProviderConfig[] = [
     id: 'github',
     name: 'GitHub',
     icon: GitHubIcon,
-    color: 'bg-gray-900 border border-gray-800',
-    hoverColor: 'hover:bg-gray-800 hover:border-gray-700',
-    textColor: 'text-white',
+    color: 'bg-white border border-gray-200',
+    hoverColor: 'hover:bg-gray-50 hover:border-gray-300',
+    textColor: 'text-gray-900',
   },
   {
     id: 'twitter',
     name: 'Twitter',
     icon: TwitterIcon,
-    color: 'bg-black border border-gray-800',
-    hoverColor: 'hover:bg-gray-900 hover:border-gray-700',
-    textColor: 'text-white',
+    color: 'bg-white border border-gray-200',
+    hoverColor: 'hover:bg-gray-50 hover:border-gray-300',
+    textColor: 'text-gray-900',
   },
   {
     id: 'discord',

app/src/pages/Welcome.tsx

@@ -1,19 +1,8 @@
-import { useState } from 'react';
-
 import OAuthProviderButton from '../components/oauth/OAuthProviderButton';
 import { oauthProviderConfigs } from '../components/oauth/providerConfigs';
 import RotatingTetrahedronCanvas from '../components/RotatingTetrahedronCanvas';
 
 const Welcome = () => {
-  const [email, setEmail] = useState('');
-
-  const handleEmailSubmit = (e: React.FormEvent) => {
-    e.preventDefault();
-    if (!email.trim()) return;
-    // TODO: implement email auth flow
-    console.log('[Welcome] email submit:', email);
-  };
-
   return (
     <div className="min-h-full flex flex-col items-center justify-center p-4">
       <div className="max-w-md w-full">
@@ -44,24 +33,20 @@ const Welcome = () => {
                 <OAuthProviderButton
                   key={provider.id}
                   provider={provider}
-                  className="!rounded-full !px-4 !py-2 !text-xs"
+                  className="!rounded-full !px-4 !py-2"
                 />
               ))}
           </div>
 
-          {/* Divider */}
+          {/* Email login — disabled until backend auth flow is implemented
           <div className="flex items-center gap-3 mb-5">
             <div className="flex-1 h-px bg-stone-200" />
             <span className="text-xs text-stone-400">Or</span>
             <div className="flex-1 h-px bg-stone-200" />
           </div>
-
-          {/* Email input + CTA */}
-          <form onSubmit={handleEmailSubmit} className="space-y-3">
+          <form className="space-y-3">
             <input
               type="email"
-              value={email}
-              onChange={e => setEmail(e.target.value)}
               placeholder="Enter your email"
               className="w-full rounded-xl border border-stone-200 bg-white px-4 py-3 text-sm text-stone-900 placeholder:text-stone-400 outline-none focus:border-primary-500 focus:ring-1 focus:ring-primary-500 transition-colors"
             />
@@ -71,6 +56,7 @@ const Welcome = () => {
               Continue with email
             </button>
           </form>
+          */}
         </div>
       </div>
     </div>