feat(voice): wire existing mic button to live speech recognition

The mic icon in AddTaskSheet was a static Image with no action and no
speech service behind it. Full implementation:

SpeechRecognizer.swift (new):
- @MainActor ObservableObject wrapping SFSpeechRecognizer + AVAudioEngine
- Requests speech recognition then microphone permission in sequence
- Streams partial results into @Published transcript; final result stops engine
- Suppresses transient error 301 (no speech detected)
- reset() cleans up on sheet dismiss
- [VOICE] log trail at every step: tapped → granted → started → transcript → saved

TodayView.swift — AddTaskSheet:
- @StateObject private var speech = SpeechRecognizer()
- onChange(speech.transcript) writes transcript to rawText (task field)
- Mic Image → Button { speech.toggle() } with mic.fill + pulse animation while recording
- .safeAreaInset shows a red dismissible error banner on permission denial
- submit() stops recording before saving; logs task title
- .onDisappear resets speech state

project.yml:
- NSMicrophoneUsageDescription
- NSSpeechRecognitionUsageDescription

Co-Authored-By: Kutesir <tqwyy79vzn@privaterelay.appleid.com>

project.yml

@@ -66,6 +66,8 @@ targets:
         INFOPLIST_KEY_NSCalendarsFullAccessUsageDescription: "Wenza shows your calendar events alongside tasks."
         INFOPLIST_KEY_NSHealthShareUsageDescription: "Wenza reads your steps, energy, heart rate, and workouts to show health stats on your dashboard."
         INFOPLIST_KEY_NSHealthUpdateUsageDescription: "Wenza saves workouts you complete to the Health app."
+        INFOPLIST_KEY_NSMicrophoneUsageDescription: "Wenza uses your microphone to convert speech into task text."
+        INFOPLIST_KEY_NSSpeechRecognitionUsageDescription: "Wenza uses speech recognition so you can add tasks by voice."
 
   KisaniCalTests:
     type: bundle.unit-test