Add manual Micropub token generation for non-PKCE clients

iA Writer's IndieAuth client predates PKCE support in the spec, so it
can't complete the normal authorization flow. Add an admin form to
mint a token directly (reusing the existing TokenService), so it can
be pasted into clients that support manual token setup instead.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017USyUg8PwuoDcHP8pv5xjy

resources/views/admin/tokens/index.blade.php

@@ -4,6 +4,15 @@
 
 @section('content')
     <h1>Micropub Tokens</h1>
+    <p><a href="/admin/tokens/create">Generate new token</a></p>
+
+    @if(session('new_token'))
+        <div class="token-reveal">
+            <p>Here's your new token. <strong>Copy it now</strong> — it won't be shown again.</p>
+            <input type="text" readonly value="{{ session('new_token') }}" onclick="this.select()">
+        </div>
+    @endif
+
     @if($tokens->isEmpty())
         <p>No tokens have been issued.</p>
     @else