feat(parser): POSIX bundling, multi-value/default validation, smarter completions; help UX & examples

- Mark help parser with `_is_help_command=True` so CLI renders as `program help`.
- Add TLDR examples to `Exit` and `History` commands.
- Normalize help TLDR/tag docs to short forms `-T` (tldr) and `-t [TAG]`.
- Also propagate submenu exit help text TLDRs when set.
- Disallow defaults for `HELP`, `TLDR`, `COUNT`, and boolean store actions.
- Enforce list defaults for `APPEND`/`EXTEND` and any `nargs` in `{int, "*", "+"}`; coerce to list when `nargs == 1`.
- Validate default(s) against `choices` (lists must be subset).
- Strengthen `choices` checking at parse-time for both scalars and lists; track invalid-choice state for UX.
- New `_resolve_posix_bundling()` with context:
  - Won’t split negative numbers or dash-prefixed positional/path values.
  - Uses the *last seen flag’s type/action* to decide if a dash token is a value vs. bundle.
- Add `_is_valid_dash_token_positional_value()` and `_find_last_flag_argument()` helpers.
- Completions overhaul
  - Track `consumed_position` and `has_invalid_choice` per-arg (via new `ArgumentState.set_consumed()` / `reset()`).
  - Add `_is_mid_value()` and `_value_suggestions_for_arg()` to produce value suggestions while typing.
  - Persist value context for multi-value args (`nargs="*"`, `"+"`) for each call to parse_args
  - Suppress suggestions when a choice is currently invalid, then recover as the prefix becomes valid.
  - Respect `cursor_at_end_of_token`; do not mutate the user’s prefix; improve path suggestions (`"."` vs prefix).
  - Better behavior after a space: suggest remaining flags when appropriate.
- Consistent `index` naming (vs `i`) and propagate `base_index` into positional consumption to mark positions accurately.
- Return value tweaks for `find_argument_by_dest()` and minor readability changes.
- Replace the minimal completion test with a comprehensive suite covering:
  - Basics (defaults, option parsing, lists, booleans).
  - Validation edges (default/choices, `nargs` list requirements).
  - POSIX bundling (flags only; negative values; dash-prefixed paths).
  - Completions for flags/values/mid-value/path/`nargs="*"` persistence.
  - `store_bool_optional` (feature / no-feature, last one wins).
  - Invalid choice suppression & recovery.
  - Repeated keywords (last one wins) and completion context follows the last.
  - File-system-backed path suggestions.
- Bumped version to 0.1.83.

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "falyx"
-version = "0.1.82"
+version = "0.1.83"
 description = "Reliable and introspectable async CLI action framework."
 authors = ["Roland Thomas Jr <roland@rtj.dev>"]
 license = "MIT"