fix: Vollbreite-Layout – max-width/margin entfernt, Content füllt Desktop-Breite

- .content: max-width:1320px + margin:auto entfernt
- padding reduziert: 36px 34px → 16px 16px
- Middle-Col (1fr) im Dashboard nutzt jetzt volle Restbreite

frontend/src/style.css

@@ -41,7 +41,7 @@ main { min-width: 0; }
 .connection.live { color: var(--green); }
 .connection.preview { color: #e6b75d; }
 .ask, .refresh { display: flex; align-items: center; gap: 7px; padding: 8px 11px; border: 1px solid #37315e; border-radius: 7px; background: #18152a; color: #c4bbff; font-size: 10px; cursor: pointer; }
-.content { max-width: 1320px; margin: auto; padding: 36px 34px 60px; }
+.content { padding: 16px 16px 60px; }
 .page-heading { display: flex; justify-content: space-between; align-items: end; margin-bottom: 28px; }
 .eyebrow, .kicker { color: #7065c8; font-size: 9px; font-weight: 700; letter-spacing: .18em; }
 h1 { margin: 7px 0 5px; font-size: 27px; letter-spacing: -.04em; }