fix: Optgroup-Styling im Imagery-Dropdown (Dark Theme)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

static/css/globe.css

@@ -573,6 +573,7 @@ html, body { height: 100%; overflow: hidden; background: var(--bg-primary); colo
 }
 .imagery-select:hover { border-color: var(--accent); }
 .imagery-select option { background: var(--bg-primary); color: var(--text); }
+.imagery-select optgroup { background: var(--bg-primary); color: var(--accent); font-style: normal; font-weight: 700; font-size: 11px; }
 
 .dot-military { background: #ff2222; box-shadow: 0 0 4px rgba(255,34,34,0.5); }
 .dot-cables { background: #00ccff; }