feat(core): clone commands and actions when binding runtimes

Add clone support across Action types and Command so commands can be safely
registered or runner-bound without mutating the original instances.

- clone BaseAction implementations across simple, composite, IO, prompt, file,
  HTTP, process, and signal actions
- bind cloned commands in Falyx.add_command_from_command() and CommandRunner
- preserve local never_prompt settings when cloning actions
- rename shared runtime state from options to options_manager for consistency
- seed root and execution option namespaces consistently
- apply scoped root and namespace option overrides during routing and dispatch
- improve namespace completion by delegating option suggestions to FalyxParser
- enrich missing-value errors and error hints

tests/test_falyx/test_exceptions.py

@@ -0,0 +1,68 @@
+import pytest
+
+from falyx.console import print_error
+from falyx.exceptions import CommandArgumentError, MissingValueError
+from falyx.parser import CommandArgumentParser
+
+
+async def test_missing_value_error_has_user_facing_message():
+    parser = CommandArgumentParser()
+    parser.add_argument("--pair", type=int, nargs=2)
+
+    with pytest.raises(MissingValueError) as exc:
+        await parser.parse_args(["--pair", "1"])
+
+    assert "pair" in str(exc.value)
+    assert "expected" in str(exc.value).lower()
+
+
+@pytest.mark.asyncio
+async def test_missing_value_error_for_fixed_nargs_has_message_and_hint():
+    parser = CommandArgumentParser()
+    parser.add_argument("--pair", type=int, nargs=2)
+
+    with pytest.raises(MissingValueError) as exc:
+        await parser.parse_args(["--pair", "1"])
+
+    error = exc.value
+
+    assert str(error) == "missing values for '--pair': expected 2, got 1"
+    assert error.hint == "provide 2 values for '--pair'."
+    assert error.show_short_usage is True
+    assert error.dest == "pair"
+
+
+@pytest.mark.asyncio
+async def test_missing_value_error_for_plus_nargs_has_message_and_hint():
+    parser = CommandArgumentParser()
+    parser.add_argument("--items", nargs="+")
+
+    with pytest.raises(MissingValueError) as exc:
+        await parser.parse_args(["--items"])
+
+    error = exc.value
+
+    assert str(error) == "missing value for '--items'"
+    assert error.hint == "provide one or more values for '--items'."
+
+
+def test_print_error_uses_exception_hint(monkeypatch) -> None:
+    printed: list[str] = []
+
+    class FakeConsole:
+        def print(self, value):
+            printed.append(value)
+
+    monkeypatch.setattr("falyx.console.error_console", FakeConsole())
+
+    error = CommandArgumentError(
+        "invalid command argument",
+        hint="use --help to see available options",
+    )
+
+    print_error(error)
+
+    assert any("error:" in line for line in printed)
+    assert any("invalid command argument" in line for line in printed)
+    assert any("hint:" in line for line in printed)
+    assert any("use --help to see available options" in line for line in printed)