feat(brand): switch user-facing copy + Mercure topic prefix to wevisto.com

Mercure topic identifiers updated in lockstep across PHP publisher + TS
subscriber (and their tests). Help-page setup instructions now point to
wevisto.com. Traefik already serves both hosts; this aligns the in-app
references with the public brand.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/Service/MercurePublisher.php

@@ -11,7 +11,7 @@ use Symfony\Component\Mercure\Update;
 /**
  * Thin wrapper around the Mercure hub for device-state pushes.
  *
- * Topic shape: `https://pictureframe.edholm.me/devices/{id}` — same convention
+ * Topic shape: `https://wevisto.com/devices/{id}` — same convention
  * aqua-iq uses. The browser subscribes per device id; the published payload is
  * the same JSON the REST API would have returned, so the SPA can splat it
  * straight into the device store with no separate envelope handling.
@@ -21,7 +21,7 @@ use Symfony\Component\Mercure\Update;
  */
 final class MercurePublisher
 {
-    public const TOPIC_PREFIX = 'https://pictureframe.edholm.me/devices/';
+    public const TOPIC_PREFIX = 'https://wevisto.com/devices/';
 
     public function __construct(
         private readonly HubInterface    $hub,