style: rename header to NestControl

Co-authored-by: Tom Ernst <tom@citr.one>

app/templates/index.html

@@ -1,7 +1,7 @@
 <!doctype html>
 <html lang="de"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1">
 <title>Sonos Steuerung</title><link rel="stylesheet" href="{{ url_for('static', filename='style.css') }}"></head>
-<body><header><div><h1>Sonos <span>zu Hause</span></h1></div><button id="refresh">↻ Räume suchen</button></header>
+<body><header><div><h1>Sonos <span>NestControl</span></h1></div><button id="refresh">↻ Räume suchen</button></header>
 <main><div id="notice" role="status" aria-live="polite"></div><section><div id="zones" class="grid"><p class="muted">Räume werden gesucht …</p></div></section>
 <section class="panel"><h2>Gruppe erstellen</h2><div class="form-grid"><label>Coordinator<select id="coordinator"></select></label><fieldset><legend>Mitglieder</legend><div id="members" class="checks"></div></fieldset></div><button id="group">Gruppe bilden</button></section>
 <section class="panel"><h2>Musik auswählen</h2><label>Raum<select id="music-zone"></select></label><div class="tabs"><button data-source="favorites" class="active">Favoriten</button><button data-source="queue">Warteschlange</button><button data-source="stream">Stream-URL</button></div><div id="music-content"></div></section></main>