feat: add recursive namespace routing and standalone runner polish

- introduce namespace-aware routing with RootParseResult, RouteResult, and InvocationContext
- register submenus as FalyxNamespace entries and resolve them through _entry_map
- refactor FalyxParser to parse only root options and leave recursive routing to Falyx
- add prepare_route, resolve_route, and route dispatch flow to Falyx
- update validator and completer to understand namespace entries and route results
- unify help/TLDR rendering APIs and add custom_tldr support on Command
- tighten Command.resolve_args error handling and parser type validation
- improve CommandRunner dependency validation and argv handling
- add BottomBar.has_items and improve wrapped executor error messages
- add tests for execution options, resolve_args, command runner, and route-aware validation

tests/test_completer/test_lcp_completions.py

@@ -17,7 +17,7 @@ def fake_falyx():
         help_command=SimpleNamespace(key="H", aliases=["HELP"]),
         history_command=SimpleNamespace(key="Y", aliases=["HISTORY"]),
         commands={"R": fake_command},
-        _name_map={"R": fake_command, "RUN": fake_command, "X": fake_command},
+        _entry_map={"R": fake_command, "RUN": fake_command, "X": fake_command},
     )