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, 5 deletions

diff --git a/crates/shirabe/src/downloader/svn_downloader.rs b/crates/shirabe/src/downloader/svn_downloader.rs
index d146337a..4931e539 100644
--- a/crates/shirabe/src/downloader/svn_downloader.rs
+++ b/crates/shirabe/src/downloader/svn_downloader.rs
@@ -15,7 +15,7 @@ use crate::util::Filesystem;
 use crate::util::ProcessExecutor;
 use crate::util::Svn as SvnUtil;
 use indexmap::IndexMap;
-use shirabe_pcre::{CaptureKey, Preg};
+use shirabe_pcre::Preg;
 use shirabe_php_shim::{
     CmpOp, PhpMixed, RuntimeException, impl_php_class, is_dir, php_regex, preg_split,
     version_compare,
@@ -384,10 +384,7 @@ impl VcsDownloader for SvnDownloader {
 
             let url_pattern = "#<url>(.*)</url>#";
             let base_url = if let Some(matches) = Preg::match3(url_pattern, &output) {
-                matches
-                    .get(&CaptureKey::ByIndex(1))
-                    .unwrap_or_default()
-                    .to_string()
+                matches.get(1).unwrap_or_default().to_string()
             } else {
                 return Err(RuntimeException::new(format!(
                     "Unable to determine svn url for path {}",