style: improve pill layout for mobile

- Wrap lesson label in span for mobile hiding
- Truncate module name with ellipsis if too long
- Hide "Lesson/Lektion" label on mobile, show only "1 / 3"
- Add lessonLabel i18n keys for EN/DE

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/main.css

@@ -243,6 +243,10 @@ code, kbd {
 .module-name {
 	text-transform: uppercase;
 	letter-spacing: 0.5px;
+	overflow: hidden;
+	text-overflow: ellipsis;
+	white-space: nowrap;
+	max-width: 150px;
 }
 
 .module-pill .level-indicator {
@@ -1079,6 +1083,14 @@ input:checked + .toggle-slider::before {
 		padding: var(--spacing-sm);
 	}
 
+	.module-name {
+		max-width: 100px;
+	}
+
+	.level-label {
+		display: none;
+	}
+
 	.btn {
 		padding: var(--spacing-xs) var(--spacing-sm);
 		font-size: 0.85rem;