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/Models/CloudProviderRole.swift

@@ -0,0 +1,12 @@
+// CloudProviderRole.swift
+// OSGKeyboard · Shared
+//
+// Distinguishes cloud ASR credentials from polish LLM credentials
+// (OpenLess-style split).
+
+import Foundation
+
+public enum CloudProviderRole: String, Sendable, Equatable {
+    case asr
+    case polish
+}