chore(immich): drop the IMMICH_URL hook

A deployment no longer suggests an address for the first server: every
address is each account's own and is typed in the app, so the field opens
blank with a placeholder. The env var, its compose passthrough, the example
line and the `defaultUrl` field that carried it are all gone; the backend's
config route now answers with the saved list alone.

docker/backend/src/immich.ts

@@ -280,16 +280,13 @@ export function immichRoutes(
     return server;
   };
 
-  // The saved list, plus the address this deployment suggests for the first one.
-  // No upstream call at all: the tree has to draw on a phone with no signal.
+  // The saved list. No upstream call at all: the tree has to draw on a phone with
+  // no signal. Nothing here suggests an address — the address and the key are each
+  // account's own, typed in the app, so a fresh server is a blank field.
   app.get('/api/immich/config', async (req, reply) => {
     const user = member(req, reply);
     if (!user) return;
-    return reply.send({
-      ok: true,
-      defaultUrl: process.env.IMMICH_URL ?? '',
-      servers: immichServers(user.id).map(view),
-    });
+    return reply.send({ ok: true, servers: immichServers(user.id).map(view) });
   });
 
   // The dialog's "check this key": nothing is stored, so a typo never becomes a