fix(ui): use middle ellipsis in HeaderPill labels

Truncated pill labels (capped city names, relay hosts) keep their
distinguishing endings, matching the codebase convention for URLs and
relay links.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AgEpNtwnetPhETXQSdq4b5

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/ui/note/HeaderPill.kt

@@ -77,7 +77,7 @@ fun HeaderPill(
                 style = MaterialTheme.typography.labelSmall,
                 color = MaterialTheme.colorScheme.placeholderText,
                 maxLines = 1,
-                overflow = TextOverflow.Ellipsis,
+                overflow = TextOverflow.MiddleEllipsis,
             )
         }
     }