Bump version to 1.3.1

Patch release: quantized Whisper models (Turbo q5_0 needs ~0.7 GB RAM
instead of ~1.75 GB), a download progress window, and model warm-up at
recording start with a HUD notice when the first transcription is slow.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

macos/Makefile

@@ -2,7 +2,7 @@
 
 APP_NAME = WhisperDictate
 APP_BUNDLE = $(APP_NAME).app
-VERSION = 1.3.0
+VERSION = 1.3.1
 
 # Directories
 SRC_DIR = src