feat: harden Flow cold-start/force-quit and polish macOS dictation UX

Fix cold-start overlay recursion that overflowed the main-thread stack when
recording began while the ready overlay was still up; also remove temporary
on-screen Flow DEBUG panels after the orange-mic investigation, and land the
macOS overlay/catalog/layout polish plus related Flow recovery hardening.

OSGKeyboardShared/Services/ASRChunkTranscribing.swift

@@ -0,0 +1,25 @@
+// ASRChunkTranscribing.swift
+// OSGKeyboard · Shared
+//
+// Minimal ASR surface for pipelined utterance chunking. Keeps
+// `ChunkedUtterancePipeline` independent of iOS-only `SpeechAnalyzer`.
+
+import Foundation
+
+public enum ASRChunkResult: Sendable, Equatable {
+    case success(String)
+    case failure(String)
+    case cancelled
+}
+
+/// One-shot chunk transcription used by `ChunkedUtterancePipeline`.
+public protocol ASRChunkTranscribing: Sendable {
+    func transcribeChunk(samples: [Float], locale: Locale) async -> ASRChunkResult
+    func cancel()
+    func resetForNewUtterance()
+}
+
+extension ASRChunkTranscribing {
+    public func cancel() {}
+    public func resetForNewUtterance() {}
+}