Bump version to 1.4.0

Minor release: live transcript preview in the recording HUD using the
on-device Apple dictation model, with Whisper still producing the final
pasted text.

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

macos/Makefile

@@ -2,7 +2,7 @@
 
 APP_NAME = WhisperDictate
 APP_BUNDLE = $(APP_NAME).app
-VERSION = 1.3.1
+VERSION = 1.4.0
 
 # Directories
 SRC_DIR = src