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.

falyx/bottom_bar.py

@@ -21,12 +21,14 @@ Key Features:
 - Columnar layout with automatic width scaling
 - Optional integration with `OptionsManager` for dynamic state toggling
 
-Usage Example:
+Example:
+    ```
     bar = BottomBar(columns=3)
     bar.add_static("env", "ENV: dev")
     bar.add_toggle("d", "Debug", get_debug, toggle_debug)
     bar.add_value_tracker("attempts", "Retries", get_retry_count)
     bar.render()
+    ```
 
 Used by Falyx to provide a persistent UI element showing toggles, system state,
 and runtime telemetry below the input prompt.