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, 29 insertions, 0 deletions

diff --git a/mingling_picker_macros/src/lib.rs b/mingling_picker_macros/src/lib.rs
index 8b13789..33bb67d 100644
--- a/mingling_picker_macros/src/lib.rs
+++ b/mingling_picker_macros/src/lib.rs
@@ -1 +1,30 @@
+use proc_macro::TokenStream;
 
+mod arg;
+mod internal_repeat;
+
+/// Core proc-macro: repeats a template body `count` times.
+///
+/// Internal call signature: `internal_repeat!(count => { template })`
+#[proc_macro]
+pub fn internal_repeat(input: TokenStream) -> TokenStream {
+    internal_repeat::internal_repeat(input)
+}
+
+/// Quick builder for `PickerArg`.
+///
+/// # Syntax
+///
+/// ```ignore
+/// use mingling_picker_macros::flag;
+///
+/// let basic = arg![name: String];
+/// let with_short_name = arg![name: String, 'n'];
+/// let with_short_alias = arg![name: String, 'n', "alias"];
+/// let positional = arg![String];
+/// let positional_with_name = arg![String, 'n', "alias"];
+/// ```
+#[proc_macro]
+pub fn arg(input: TokenStream) -> TokenStream {
+    arg::arg(input)
+}