refactor(cli): improve CLI default command handling

Make 'crawl' the default command when no command is specified.
This improves user experience by allowing direct URL input without
explicitly specifying the 'crawl' command.

Also removes unnecessary blank lines in example code for better readability.

crawl4ai/cli.py

@@ -712,7 +712,7 @@ def profiles_cmd():
     # Run interactive profile manager
     anyio.run(manage_profiles)
 
-@cli.command()
+@cli.command(name="")
 @click.argument("url", required=False)
 @click.option("--example", is_flag=True, help="Show usage examples")
 @click.option("--browser-config", "-B", type=click.Path(exists=True), help="Browser config file (YAML/JSON)")
@@ -772,5 +772,11 @@ def default(url: str, example: bool, browser_config: str, crawler_config: str, f
         profile=profile
     )
 
+def main():
+    import sys
+    if len(sys.argv) < 2 or sys.argv[1] not in cli.commands:
+        sys.argv.insert(1, "crawl")
+    cli()
+
 if __name__ == "__main__":
-    cli()
+    main()