feat(macos): launcher rename, Dock icon, hide-to-tray window lifecycle

A bare `python main_qml.py` launch surfaces "python" in the Dock tile,
Cmd+Tab caption, Force Quit, and Activity Monitor because macOS reads
the Mach-O image basename at exec time and there is no in-process API
to rename it after the fact. The application icon comes from the same
bundle identity, so the Dock also shows the generic Python launcher
icon instead of Mouser's branding. None of this affects PyInstaller
`.app` bundles -- only source and venv launches.

The fix layers a few small pieces in main_qml.py.
`_maybe_relaunch_with_mouser_process_name` re-execs the current
interpreter through a stable symlink whose basename is `Mouser`, staged
atomically via os.replace() to avoid a TOCTOU window where a concurrent
launch could observe the launcher path missing. The symlink lives next
to the venv's python shim so pyvenv.cfg discovery still resolves
site-packages after the re-exec. It returns immediately on
PyInstaller-frozen bundles (where the Mach-O is already correctly
named), on non-macOS platforms, and when the env-var guard shows we
already relaunched. `_rename_macos_bundle_for_dock` mutates
[NSBundle mainBundle]'s display-name keys so the application menu,
Force Quit, and notification banners read "Mouser" as well.

`_install_macos_dock_icon` replaces NSApplication's icon with
`images/logo_icon.png`. The decoded NSImage is cached at module scope
so repeated invocations (one per Regular promotion) only re-issue the
cheap setApplicationIconImage_ syscall instead of re-decoding the
1024px PNG. `_app_icon` similarly hands QIcon the full-resolution PNG
directly so the Dock and Cmd+Tab tiles render crisply at native size
instead of the previous upscaled-256px blur.

`_configure_macos_app_mode` and `_set_macos_activation_policy` launch
the app as NSApplicationActivationPolicyAccessory (menu-bar only, no
Dock entry), then promote to Regular when a window becomes visible.
The visibilityChanged hook flips back to Accessory on hide so the Dock
collapses cleanly. The policy setter is idempotent against rapid
visibilityChanged storms by skipping the AppKit round-trip when the
requested state matches the last-applied one.

`_check_accessibility` fails closed on exception now (returns False)
so future callers can rely on the docstring contract, and
`_parse_cli_args` returns a 4-tuple so callers can branch on the new
`--show-window` flag.

Author: hughesyadaddy