Remove Immich URL/API key from the config page

Now that they're set via docker-compose.yml's environment (previous
commit), leaving editable fields for them on the page was misleading --
anything typed there would be silently overwritten by the env vars on the
next load() anyway. Replaced with a read-only info banner showing the
configured Immich URL (never the API key value, even though it's already
env-sourced rather than user input) or a warning if IMMICH_URL/
IMMICH_API_KEY aren't set. POST /api/config no longer accepts or touches
those two fields at all.

Verified: page renders with no immich_url/immich_api_key input fields or
API key value in either case (env vars set or unset); config save/albums/
frame-image still work end-to-end via a mock Immich server.

server/app/main.py

@@ -61,16 +61,16 @@ def api_albums():
 
 @app.post("/api/config")
 def api_config_save(
-    immich_url: str = Form(""),
-    immich_api_key: str = Form(""),
     album_id: str = Form(""),
     order: str = Form("sequential"),
     refresh_interval_s: int = Form(3600),
     smart_crop_faces: bool = Form(True),
 ):
+    # Immich URL/API key are env-var only (IMMICH_URL/IMMICH_API_KEY, see
+    # docker-compose.yml.example) -- config.load() already applies them,
+    # and this handler doesn't touch cfg.immich_url/immich_api_key at all,
+    # so there's nothing here that could overwrite or clear them.
     cfg = config.load()
-    cfg.immich_url = immich_url.strip()
-    cfg.immich_api_key = immich_api_key.strip()
     if album_id != cfg.album_id:
         cfg.cursor = 0  # restart from the top of a newly selected album
     cfg.album_id = album_id

server/app/templates/index.html

@@ -19,6 +19,8 @@
     .status { margin-top: 16px; padding: 10px; border-radius: 4px; font-size: 14px; }
     .status.ok { background: #dcfce7; color: #166534; }
     .status.err { background: #fee2e2; color: #991b1b; }
+    .info-box { margin-top: 16px; padding: 10px; border-radius: 4px; font-size: 13px; background: #f3f4f6; color: #444; }
+    .info-box.warn { background: #fef9c3; color: #854d0e; }
     code { background: #f3f4f6; padding: 2px 5px; border-radius: 3px; }
   </style>
 </head>
@@ -26,13 +28,17 @@
   <h1>ESPresso Frame</h1>
   <p class="sub">Point your frame's "Tools Server" field at this server's <code>host:port</code>.</p>
 
+  {% if cfg.immich_url %}
+    <div class="info-box">Immich: <code>{{ cfg.immich_url }}</code> (API key configured). Set via
+      <code>IMMICH_URL</code>/<code>IMMICH_API_KEY</code> in <code>docker-compose.yml</code> -- see
+      <code>docker-compose.yml.example</code>.</div>
+  {% else %}
+    <div class="info-box warn">Immich isn't configured yet. Set <code>IMMICH_URL</code> and
+      <code>IMMICH_API_KEY</code> in <code>docker-compose.yml</code> (copy
+      <code>docker-compose.yml.example</code>) and restart the server.</div>
+  {% endif %}
+
   <form id="config-form">
-    <label>Immich URL
-      <input type="text" id="immich_url" value="{{ cfg.immich_url }}" placeholder="http://192.168.1.10:2283" required>
-    </label>
-    <label>Immich API Key
-      <input type="password" id="immich_api_key" value="{{ cfg.immich_api_key }}" required>
-    </label>
     <label>Album
       <select id="album_id">
         {% if cfg.album_id %}<option value="{{ cfg.album_id }}" selected>(current selection -- reload to rename)</option>{% endif %}
@@ -67,8 +73,6 @@
     async function saveConfig() {
       const minutes = parseInt(document.getElementById('refresh_interval_minutes').value, 10) || 60;
       const body = new URLSearchParams({
-        immich_url: document.getElementById('immich_url').value,
-        immich_api_key: document.getElementById('immich_api_key').value,
         album_id: document.getElementById('album_id').value || '',
         order: document.getElementById('order').value,
         refresh_interval_s: String(minutes * 60),