feat(picker2): complete Picker2 prototype

Picker2 replaces the original Picker1 with a two-phase (tag → pick) +
mask-bitmap architecture, decoupling argument matching from type
conversion via a composable matcher pipeline.

Architecture
- FlagMatcher — boolean flags (--verbose)
- ArgMatcher — single flag+value pairs (--name Alice)
- MultiArgMatcher — multi-value flag groups (--files a.txt b.txt)
- PositionalMatcher — positional arguments, respects `--`
- SingleMatcher — composite for Single-type Pickables

Types
- Flag (Active/Inactive) — semantic bool flag value
- String + 14 numeric types via SinglePickable trait
- Vec<T> — greedy multi-value (all SinglePickable types)
- VecUntil<T> — bounded multi-value via BoundaryCheck trait
- VecUntil<T>, pick_string, pick_numbers, pick_bool, pick_flag

Style system
- UNIX_STYLE (kebab), POWERSHELL_STYLE (Pascal), WINDOWS_STYLE (Pascal)
- naming_case auto-conversion via just_fmt integration
- Style-aware separator (= for Unix, : for PS/Windows)

Infrastructure
- internal_repeat! macro generates PickerPattern1..=32
- SinglePickable blanket impl → Pickable
- MultiPickableWithBoundary trait with greedy/bounded variants
- 151 integration tests
- Docs updated for parser feature

1 files changed, 77 insertions, 0 deletions

diff --git a/mingling_picker/src/pickable/multi_pickable.rs b/mingling_picker/src/pickable/multi_pickable.rs
new file mode 100644
index 0000000..0ab0508
--- /dev/null
+++ b/mingling_picker/src/pickable/multi_pickable.rs
@@ -0,0 +1,77 @@
+use crate::{
+    matcher_needed::Matcher,
+    parselib::{MultiArgMatcher, ParserStyle},
+    Pickable, PickerArg, PickerArgAttr, PickerArgResult,
+    SinglePickable, TagPhaseContext,
+};
+
+/// Boundary check for multi-value positional parameters.
+pub trait BoundaryCheck {
+    fn check_boundary(raw: &str) -> bool;
+}
+
+/// Trait for multi-value parameters.
+pub trait MultiPickableWithBoundary: Sized {
+    type Checker: BoundaryCheck;
+    fn pick_multi(raw: Vec<String>) -> PickerArgResult<Self>;
+}
+
+/// Marker: unit type that always accepts — no boundary.
+pub struct NoBoundary;
+
+impl BoundaryCheck for NoBoundary {
+    #[inline(always)]
+    fn check_boundary(_raw: &str) -> bool {
+        false
+    }
+}
+
+/// `Vec<T>` is greedy — it takes everything with `NoBoundary`.
+impl<T: SinglePickable> MultiPickableWithBoundary for Vec<T> {
+    type Checker = NoBoundary;
+
+    fn pick_multi(raw: Vec<String>) -> PickerArgResult<Self> {
+        let mut result = Vec::with_capacity(raw.len());
+        for s in &raw {
+            match T::pick_single(Some(s)) {
+                PickerArgResult::Parsed(v) => result.push(v),
+                PickerArgResult::NotFound => return PickerArgResult::NotFound,
+                PickerArgResult::Unparsed => {}
+            }
+        }
+        PickerArgResult::Parsed(result)
+    }
+}
+
+/// If the first raw string looks like a named flag (starts with the
+/// style's long or short prefix), strip it — it's the flag, not a value.
+fn strip_flag<'a>(raw_strs: &'a [&'a str]) -> &'a [&'a str] {
+    if let Some(first) = raw_strs.first() {
+        let style = ParserStyle::global_style();
+        if first.starts_with(style.long_prefix) || first.starts_with(style.short_prefix) {
+            return &raw_strs[1..];
+        }
+    }
+    raw_strs
+}
+
+// Pickable impl for Vec<T>
+
+impl<'a, T> Pickable<'a> for Vec<T>
+where
+    T: SinglePickable,
+{
+    fn get_attr(flag: &'a PickerArg<'a, Self>) -> PickerArgAttr {
+        PickerArgAttr::positional_or_multi(flag)
+    }
+
+    fn tag(ctx: TagPhaseContext) -> Vec<usize> {
+        MultiArgMatcher::match_all(ctx.into())
+    }
+
+    fn pick(raw_strs: &[&str]) -> PickerArgResult<Self> {
+        let strs = strip_flag(raw_strs);
+        let owned: Vec<String> = strs.iter().map(|&s| s.to_string()).collect();
+        <Vec<T> as MultiPickableWithBoundary>::pick_multi(owned)
+    }
+}