macOS: set speech recognition taskHint for Talk Mode mic capture

Add taskHint = .dictation to Talk Mode's SFSpeechAudioBufferRecognitionRequest,
matching what Voice Wake already sets. Without this hint the recognizer may not
properly initialize audio capture, causing Talk Mode to appear unresponsive.

Co-Authored-By: dmiv <dmiv@users.noreply.github.com>

apps/macos/Sources/OpenClaw/TalkModeRuntime.swift

@@ -178,6 +178,7 @@ actor TalkModeRuntime {
 
         self.recognitionRequest = SFSpeechAudioBufferRecognitionRequest()
         self.recognitionRequest?.shouldReportPartialResults = true
+        self.recognitionRequest?.taskHint = .dictation
         guard let request = self.recognitionRequest else { return }
 
         if self.audioEngine == nil {