refactor(symfony-string): extract symfony/string into the shirabe-symfony-string crate

Move `Symfony\Component\String` out of shirabe-external-packages and into
its own crate, so the path is `shirabe_symfony_string::ByteString`
instead of `shirabe_external_packages::symfony::string::ByteString`.

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

1 files changed, 1 insertions, 0 deletions

diff --git a/Cargo.toml b/Cargo.toml
index 1da42453..d304b273 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -17,6 +17,7 @@ shirabe-php-shim = { path = "crates/shirabe-php-shim" }
 shirabe-php-src = { path = "crates/shirabe-php-src" }
 shirabe-semver = { path = "crates/shirabe-semver" }
 shirabe-spdx-licenses = { path = "crates/shirabe-spdx-licenses" }
+shirabe-symfony-string = { path = "crates/shirabe-symfony-string" }
 anyhow = "1.0.102"
 async-trait = "0.1.89"
 base64 = "0.22.1"