feat: add path completion, LCP-based suggestions, and validator tests

- Refactored `FalyxCompleter` to support longest common prefix (LCP) completions by default.
- Added `_ensure_quote` helper to auto-quote completions containing spaces/tabs.
- Integrated `_yield_lcp_completions` for consistent completion insertion logic.
- Added `_suggest_paths()` helper to dynamically suggest filesystem paths for arguments of type `Path`.
- Integrated path completion into `suggest_next()` for both positional and flagged arguments.
- Updated `argument_examples.py` to include a `--path` argument (`Path | None`), demonstrating file path completion.
- Enabled `CompleteStyle.COLUMN` for tab-completion menu formatting in interactive sessions.
- Improved bottom bar docstring formatting with fenced code block examples.
- Added safeguard to `word_validator` to reject `"N"` since it’s reserved for `yes_no_validator`.
- Improved help panel rendering for commands (using `Padding` + `Panel`).
- Added full test coverage for:
  - `FalyxCompleter` and LCP behavior (`tests/test_completer/`)
  - All validators (`tests/test_validators/`)
- Bumped version to 0.1.80.

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "falyx"
-version = "0.1.79"
+version = "0.1.80"
 description = "Reliable and introspectable async CLI action framework."
 authors = ["Roland Thomas Jr <roland@rtj.dev>"]
 license = "MIT"