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, 2 insertions, 8 deletions

diff --git a/crates/shirabe/src/util/filesystem.rs b/crates/shirabe/src/util/filesystem.rs
index 6302a6d2..2ef51ba1 100644
--- a/crates/shirabe/src/util/filesystem.rs
+++ b/crates/shirabe/src/util/filesystem.rs
@@ -739,10 +739,7 @@ impl Filesystem {
             php_regex!("{^( [0-9a-z]{2,}+: (?: // (?: [a-z]: )? )? | [a-z]: )}ix"),
             &path,
         ) {
-            prefix = prefix_match
-                .get(&shirabe_pcre::CaptureKey::ByIndex(1))
-                .unwrap_or_default()
-                .to_string();
+            prefix = prefix_match.get(1).unwrap_or_default().to_string();
             path = substr(&path, strlen(&prefix), None);
         }
 
@@ -766,10 +763,7 @@ impl Filesystem {
         prefix = Preg::replace_callback(
             php_regex!("{(^|://)[a-z]:$}i"),
             |m: &shirabe_pcre::PregMatches| -> String {
-                let s = m
-                    .get(&shirabe_pcre::CaptureKey::ByIndex(0))
-                    .unwrap_or_default()
-                    .to_string();
+                let s = m.get(0).unwrap_or_default().to_string();
                 strtoupper(&s)
             },
             &prefix,