feat(keyboard): improve typing, voice flow, and polish reliability

Reduce extension memory pressure and delivery races while adding richer candidates, tactile feedback, and safer two-level creative polishing.

OSGKeyboardShared/Models/AudioBufferSnapshot.swift

@@ -2,12 +2,10 @@
 // OSGKeyboard · Shared
 //
 // Sendable wrapper around a Float32 audio buffer's raw samples.
-// The snapshot is the only thing that crosses actor / concurrency
-// boundaries; the recognizer re-creates an `AVAudioPCMBuffer` on its
-// own side and consumes it locally (never yielding it back out).
+// Lives in Shared (no AVFoundation) so utterance chunking stays extension-safe.
+// The AVAudioPCMBuffer initializer lives in OSGKeyboardHostSupport.
 
 import Foundation
-import AVFoundation
 
 public struct AudioBufferSnapshot: Sendable {
     public let samples: [Float]
@@ -17,18 +15,4 @@ public struct AudioBufferSnapshot: Sendable {
         self.samples = samples
         self.sampleRate = sampleRate
     }
-
-    /// Construct from an `AVAudioPCMBuffer` by copying out the channel data.
-    public init(buffer: AVAudioPCMBuffer) {
-        guard let channelData = buffer.floatChannelData else {
-            self.samples = []
-            self.sampleRate = buffer.format.sampleRate
-            return
-        }
-        let n = Int(buffer.frameLength)
-        var copy = [Float](repeating: 0, count: n)
-        memcpy(&copy, channelData[0], n * MemoryLayout<Float>.size)
-        self.samples = copy
-        self.sampleRate = buffer.format.sampleRate
-    }
 }