Add a Mac as the third system, beside Wayland and X11

Dikte already chose its clipboard programs once instead of in every
function; macOS joins that table rather than adding a branch to each one.
A Mac copies through pbcopy and presses Cmd+V straight into CoreGraphics,
records through AVFoundation, and asks Carbon for its global shortcuts.

The three tables are paste.Desktop, audio.Sound, and the pair of
predicates in hotkey.py. Each reads sys.platform inside the chooser, so a
test can stand somewhere else: 697 of the 737 tests now run on any
machine, the Wayland and X11 halves included, and the suite passes whole
whichever system it is run on.

Two things a Mac does not have needed saying rather than pretending:
there is no shortcut registry to install into, so Settings offers no
Install button and the listener is the mechanism instead of a fallback;
and nothing is offered as the sound the speakers are playing, so a
meeting needs BlackHole or Loopback and says so. The KDE-only labels
around them were already wrong on GNOME, and now name whichever desktop
is there.

Co-authored-by: firat <[email protected]>

config.py

@@ -1,21 +1,35 @@
-"""Settings storage in ~/.config/dikte/config.json"""
+"""Settings storage, in the place this system keeps a program's settings."""
 
 import hashlib
 import json
 import os
 import pathlib
+import sys
 
 import api
 import i18n
+import paste
 
 
 def _xdg(var, default):
     return pathlib.Path(os.environ.get(var) or os.path.expanduser(default))
 
 
-CONFIG_DIR = _xdg("XDG_CONFIG_HOME", "~/.config") / "dikte"
+def _directories(platform=None):
+    """(settings, data), in the two places this system keeps them.
+
+    macOS keeps both in the one directory a Mac user's backup already knows
+    about. Everywhere else they are separate and follow the XDG variables.
+    """
+    if (platform or sys.platform) == "darwin":
+        support = pathlib.Path.home() / "Library/Application Support/Dikte"
+        return support, support
+    return (_xdg("XDG_CONFIG_HOME", "~/.config") / "dikte",
+            _xdg("XDG_DATA_HOME", "~/.local/share") / "dikte")
+
+
+CONFIG_DIR, DATA_DIR = _directories()
 CONFIG_FILE = CONFIG_DIR / "config.json"
-DATA_DIR = _xdg("XDG_DATA_HOME", "~/.local/share") / "dikte"
 HISTORY_FILE = DATA_DIR / "history.jsonl"
 RECORDINGS_DIR = DATA_DIR / "recordings"
 MEETINGS_DIR = DATA_DIR / "meetings"
@@ -375,7 +389,7 @@ DEFAULTS = {
     "cleanup_reasoning": "",        # empty -> whatever the model does by default
     "cleanup_prompt": "",           # empty -> language-specific default
     "auto_paste": True,
-    "paste_shortcut": "ctrl+v",
+    "paste_shortcut": paste.desktop().shortcuts[0],   # cmd+v on a Mac
     "restore_clipboard": False,
     "mic_target": "",
     "max_seconds": 300,