Rename `bool_matcher` module to `flag_matcher` and introduce a dedicated
`FlagMatcher` struct, moving matching logic away from the `bool` type
itself

Add `Pickable` implementation for `bool` and the supporting `Matcher`
trait
with utility functions for argument matching.  Expose `pickable_needed`
and
`matcher_needed` modules for downstream trait implementors.

Introduce `get_attr`, `tag`, and `pick` as the new trait methods,
replacing
the single `tag` method that returned a `PickerTag`.  This enables the
parser to first collect all argument position requirements and then
resolve
them in a second pass.

Rename `PickerTag` to `PickerArgInfo` and reorder `PickerFlagAttr`
variants
to reflect parse priority (`Positional < Flag < Single < Multi`).  Add
`positional_or_else` helper to `PickerFlagAttr`.

Add a configurable `ParserStyle` struct defining option prefix,
separator
and case-sensitivity conventions, with built-in constants for Unix,
PowerShell and Windows styles. Provide a one-time global style setter.

Re-export the new `parselib` module from `mingling_picker` and wire it
through `mingling`'s `picker` facade. Also relocate `Groupped` and
`RenderResult` re-exports in `prelude` for better ordering.