test(cli): cover UsageError path in main() and drop redundant handler

The mro-based UsageError check inside the Exception block already
catches BadParameter (it inherits from UsageError) — the separate
typer.BadParameter handler was redundant.

Added an in-process Behave step that calls main() directly and
captures err_console output, plus a scenario that runs
`plan use --no-such-flag` to cover the UsageError branch (subprocess
steps do not count toward unit-test coverage).

features/main_error_paths.feature

@@ -35,3 +35,9 @@ Feature: CLI main() error handling paths
   Scenario: _print_basic_help prints without error
     When I call the main _print_basic_help
     Then the main _print_basic_help completes ok
+
+  @coverage
+  Scenario: unknown option triggers UsageError handler with exit code 2
+    When I call main with arguments ["plan", "use", "--no-such-flag", "x"]
+    Then the main cli exit code should be 2
+    And the main cli output contains "No such option"

features/steps/main_error_paths_steps.py

@@ -85,6 +85,23 @@ def step_print_basic_help(context: Context) -> None:
     context.help_output = buf.getvalue()
 
 
+@when("I call main with arguments {args}")
+def step_main_in_process(context: Context, args: str) -> None:
+    """Call ``main(args)`` in-process so coverage tracks the exception paths."""
+    from cleveragents.cli.main import get_err_console, main
+
+    cmd_args = ast.literal_eval(args) if isinstance(args, str) else []
+    console = get_err_console()
+    buf = StringIO()
+    original_file = console.file
+    console.file = buf
+    try:
+        context.exit_code = main(cmd_args)
+    finally:
+        console.file = original_file
+    context.output = buf.getvalue()
+
+
 # ---------------------------------------------------------------------------
 # Then steps — unique step texts to avoid collisions with other suites
 # ---------------------------------------------------------------------------

src/cleveragents/cli/main.py

@@ -813,10 +813,6 @@ def main(args: list[str] | None = None) -> int:
         err_console = get_err_console()
         err_console.print("\n[yellow]Interrupted by user[/yellow]")
         return 130
-    except typer.BadParameter as e:
-        err_console = get_err_console()
-        err_console.print(f"Error: {e.format_message()}")
-        return 2
     except Exception as e:
         if any(c.__name__ == "UsageError" for c in type(e).__mro__) and hasattr(
             e, "format_message"