Add .labui file association — open by double-click, cross-platform

Windows/Linux self-register via core/file_association.py (winreg /
XDG .desktop+mime), triggered from a new Settings button since there's
no installer to do it at install time. macOS gets it at build time via
labui.spec's new BUNDLE() step (CFBundleDocumentTypes in Info.plist) —
that step also makes mac builds a real .app bundle for the first time,
not just a bare onedir folder. main.py gains a LabUIApplication
subclass to catch the macOS QFileOpenEvent (buffered if it arrives
before MainWindow exists) plus argv[1] handling for Windows/Linux.
ProfileButton.load_path() extracted so both paths share the same
load-and-apply logic as the existing file-dialog flow.

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

1 files changed, 8 insertions, 0 deletions

diff --git a/ui/profile_manager_ui.py b/ui/profile_manager_ui.py
index 446e867..79f333e 100644
--- a/ui/profile_manager_ui.py
+++ b/ui/profile_manager_ui.py
@@ -85,13 +85,21 @@ class ProfileButton(QPushButton):
         )
         if not path:
             return
+        self.load_path(path)
+
+    def load_path(self, path: str) -> bool:
+        """Load a profile from an explicit path — shared by the file dialog
+        above and by opening a .labui file from the OS (double-click / CLI
+        argv), see main.py."""
         try:
             profile = Profile.load(path)
             self._apply_profile(profile)
             self._current_path = path
             self._update_title(profile.name)
+            return True
         except Exception as e:
             QMessageBox.critical(self, "Load Failed", str(e))
+            return False
 
     def _do_save(self):
         if not self._current_path: