Fix Click deprecation warning, use standard invoke_without_command pattern

mosaic.py

@@ -158,17 +158,7 @@ def _load_profiles_fallback() -> list[dict]:
 # Click CLI
 # ---------------------------------------------------------------------------
 
-class MosaicCLI(click.Group):
+@click.group(invoke_without_command=True)
-    """Custom group that shows the interactive menu when invoked bare."""
-
-    def invoke(self, ctx):
-        if not ctx.protected_args and not ctx.invoked_subcommand:
-            interactive_menu(ctx)
-        else:
-            super().invoke(ctx)
-
-
-@click.group(cls=MosaicCLI, invoke_without_command=True)
 @click.option("--source", type=str, default=None, help="Source profile name.")
 @click.option("--url", type=str, default=None, help="Ad-hoc source URL.")
 @click.option("--profile", "profile_path", type=click.Path(exists=True), default=None,
@@ -205,6 +195,9 @@ def cli(ctx, source, url, profile_path, dry_run, retry_failed, since, date_range
     ctx.obj["verbose"] = verbose
     ctx.obj["output_dir"] = get_output_dir(cfg)
 
+    if ctx.invoked_subcommand is None:
+        interactive_menu(ctx)
+
 
 # ---------------------------------------------------------------------------
 # collect