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, 1 deletions

diff --git a/crates/shirabe/src/util/http/response.rs b/crates/shirabe/src/util/http/response.rs
index 7c5f5248..bd117a24 100644
--- a/crates/shirabe/src/util/http/response.rs
+++ b/crates/shirabe/src/util/http/response.rs
@@ -66,7 +66,7 @@ impl Response {
         let pattern = format!("{{^{}:\\s*(.+?)\\s*$}}i", preg_quote(name, None));
         for header in headers {
             if let Some(matches) = Preg::match3(&pattern, header)
-                && let Some(s) = matches.get(&shirabe_pcre::CaptureKey::ByIndex(1))
+                && let Some(s) = matches.get(1)
             {
                 value = Some(s.to_string());
             }