refactor(macos): dedupe UI, pairing, and runtime helpers

apps/macos/Sources/OpenClaw/VoiceOverlayTextFormatting.swift

@@ -0,0 +1,27 @@
+import AppKit
+
+enum VoiceOverlayTextFormatting {
+    static func delta(after committed: String, current: String) -> String {
+        if current.hasPrefix(committed) {
+            let start = current.index(current.startIndex, offsetBy: committed.count)
+            return String(current[start...])
+        }
+        return current
+    }
+
+    static func makeAttributed(committed: String, volatile: String, isFinal: Bool) -> NSAttributedString {
+        let full = NSMutableAttributedString()
+        let committedAttr: [NSAttributedString.Key: Any] = [
+            .foregroundColor: NSColor.labelColor,
+            .font: NSFont.systemFont(ofSize: 13, weight: .regular),
+        ]
+        full.append(NSAttributedString(string: committed, attributes: committedAttr))
+        let volatileColor: NSColor = isFinal ? .labelColor : NSColor.tertiaryLabelColor
+        let volatileAttr: [NSAttributedString.Key: Any] = [
+            .foregroundColor: volatileColor,
+            .font: NSFont.systemFont(ofSize: 13, weight: .regular),
+        ]
+        full.append(NSAttributedString(string: volatile, attributes: volatileAttr))
+        return full
+    }
+}