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_completion_contract.py

@@ -0,0 +1,121 @@
+from prompt_toolkit.document import Document
+
+from falyx import Falyx
+from falyx.completer import FalyxCompleter
+from falyx.parser import CommandArgumentParser
+
+
+def completion_texts(completions) -> list[str]:
+    return [c.text for c in completions]
+
+
+def make_completion_app() -> tuple[Falyx, FalyxCompleter]:
+    flx = Falyx(program="falyx")
+
+    flx.add_option(
+        "--profile",
+        suggestions=["dev", "prod", "staging"],
+        help="Runtime profile",
+    )
+
+    flx.add_option(
+        "--region",
+        choices=["us-east", "us-west"],
+        help="Deployment region",
+    )
+
+    parser = CommandArgumentParser()
+    parser.add_argument("--name")
+    parser.add_argument("--env", choices=["dev", "prod"])
+
+    flx.add_command(
+        key="D",
+        description="Deploy",
+        action=lambda name, env: f"deploy {name} to {env}",
+        aliases=["deploy"],
+        arg_parser=parser,
+    )
+
+    return flx, FalyxCompleter(flx)
+
+
+def test_completion_suggests_namespace_flags():
+    _, completer = make_completion_app()
+
+    completions = list(
+        completer.get_completions(Document(text="--pr", cursor_position=4), None)
+    )
+
+    texts = completion_texts(completions)
+    assert "--profile" in texts
+
+
+def test_completion_suggests_namespace_option_values():
+    _, completer = make_completion_app()
+
+    completions = list(
+        completer.get_completions(
+            Document(text="--profile pr", cursor_position=len("--profile pr")),
+            None,
+        )
+    )
+
+    texts = completion_texts(completions)
+    assert "prod" in texts
+    assert "dev" not in texts
+
+
+def test_completion_after_committed_namespace_option_returns_namespace_entries():
+    _, completer = make_completion_app()
+
+    completions = list(
+        completer.get_completions(
+            Document(text="--profile prod de", cursor_position=len("--profile prod de")),
+            None,
+        )
+    )
+
+    texts = completion_texts(completions)
+    assert "deploy" in texts
+
+
+def test_completion_preview_mode_prefixes_namespace_entry_suggestions():
+    _, completer = make_completion_app()
+
+    completions = list(
+        completer.get_completions(Document(text="?de", cursor_position=3), None)
+    )
+
+    texts = completion_texts(completions)
+    assert "?deploy" in texts
+
+
+def test_resolve_completion_route_unresolved_entry_with_trailing_input_stops_namespace_entry_mode():
+    flx, _ = make_completion_app()
+
+    route = flx.resolve_completion_route(
+        ["wat"],
+        stub="--na",
+        cursor_at_end_of_token=False,
+        invocation_context=flx.get_current_invocation_context(),
+        is_preview=False,
+    )
+
+    assert route.command is None
+    assert route.expecting_entry is False
+    assert route.remaining_argv == ["wat", "--na"]
+    assert route.stub == ""
+
+
+def test_completion_delegates_to_command_parser_after_leaf_command_is_resolved():
+    _, completer = make_completion_app()
+
+    completions = list(
+        completer.get_completions(
+            Document(text="D --na", cursor_position=len("D --na")),
+            None,
+        )
+    )
+
+    texts = completion_texts(completions)
+    assert "--name" in texts