refactor(preg): split PregMatches reads into get() and name()

PregMatches keyed both forms of a capture group through CaptureKey, so
every read built one: a usize wrapped in an enum, or worse, a String
allocated to name a group that regex::Captures can look up from a &str.
It now mirrors regex::Captures instead -- get() takes the group number,
name() the group name -- and the enum drops out of the type entirely.

That is 285 call sites across 59 files, and the named ones carry most of
the win: `matches.get(&CaptureKey::ByName("host".to_string()))` reads as
`matches.name("host")`. ProcessExecutor loses a `user_key` binding that
existed only to build the key once.

CaptureKey stays as the key type of PregMatchesAll and
PregMatchesAllWithOffsets, where numbered and named entries share one
IndexMap and a key type is the point. Five files still name it.

Also retargets the two preg_match_all comments that described the
occurrence count through `matches[&CaptureKey::ByIndex(0)].len()`, an
Index impl these types no longer carry.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

1 files changed, 1 insertions, 5 deletions

diff --git a/crates/shirabe/src/dependency_resolver/lock_transaction.rs b/crates/shirabe/src/dependency_resolver/lock_transaction.rs
index 810c19af..a238f2d6 100644
--- a/crates/shirabe/src/dependency_resolver/lock_transaction.rs
+++ b/crates/shirabe/src/dependency_resolver/lock_transaction.rs
@@ -177,11 +177,7 @@ impl LockTransaction {
                 let new_dist_url = Preg::replace_callback(
                     php_regex!(r"{(/|sha=)[a-f0-9]{40}(/|$)}i"),
                     |m: &shirabe_pcre::PregMatches| -> String {
-                        let get = |i: usize| -> String {
-                            m.get(&shirabe_pcre::CaptureKey::ByIndex(i))
-                                .unwrap_or_default()
-                                .to_string()
-                        };
+                        let get = |i: usize| -> String { m.get(i).unwrap_or_default().to_string() };
                         format!("{}{}{}", get(1), dist_reference, get(2))
                     },
                     &package.get_dist_url().unwrap(),