Insertion-order-dependent false prefix-suffix conflict with bare param

[ck961018]

Reproduction

use matchit::Router;

fn main() {
    let mut r1 = Router::new();
    r1.insert("/foo{a}", 1).unwrap();
    assert!(r1.insert("/{a}/bar", 2).is_err()); // Conflict

    let mut r2 = Router::new();
    r2.insert("/{a}/bar", 2).unwrap();
    r2.insert("/foo{a}", 1).unwrap(); // OK
}

Also fails for /foo{a} then /{a}/{b}.

Suspected cause

The wildcard branch (src/tree.rs:390-398) has the same prefix-suffix check that commit 500698f fixed for the static branch, but still slices the suffix past the end of the segment:

let suffix = remaining.slice_off(wildcard.end);   // line 392
if !matches!(*suffix, b"" | b"/") && node.prefix_wild_child_in_segment() {
    return Err(InsertError::conflict(&route, remaining, node));
}

For /{a}/bar, suffix becomes /bar, so it conflicts with the existing /foo{a}. The segment-local suffix should be /.

The static branch already limits this check to the segment (src/tree.rs:313-327):

let terminator = remaining.iter().position(|&b| b == b'/').unwrap_or(remaining.len());
let suffix = remaining.slice_until(terminator).slice_off(wildcard.end);