Don't double-label voices whose name already carries the quality tier

Premium/enhanced voices ship with the tier in their name (e.g. "Ava
(Premium)"), so appending "— Premium" produced "Ava (Premium) — Premium"
in the voice picker. Move the label logic to SpeechSettings.displayLabel
and skip the suffix when the name already contains the tier (still
name-only for default voices). Deterministic string helper, unit-tested.

Claude-Session: https://claude.ai/code/session_01BQcEWmAPA78338QuEwRkAh

Workouts/Speech/SpeechSettings.swift

@@ -100,6 +100,16 @@ enum SpeechSettings {
         @unknown default: "Default"
         }
     }
+
+    /// The picker label for a voice: its name, with the quality tier appended only when it
+    /// adds information. Default voices get no suffix (labeling every one "Default" is noise),
+    /// and enhanced/premium voices whose name already carries the tier — e.g. "Ava (Premium)" —
+    /// aren't labeled twice.
+    static func displayLabel(name: String, quality: AVSpeechSynthesisVoiceQuality) -> String {
+        guard quality != .default else { return name }
+        let label = qualityLabel(quality)
+        return name.localizedCaseInsensitiveContains(label) ? name : "\(name) — \(label)"
+    }
 }
 
 private extension AVSpeechSynthesisVoiceQuality {