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, 17 insertions, 0 deletions

diff --git a/crates/shirabe-symfony-string/src/lib.rs b/crates/shirabe-symfony-string/src/lib.rs
new file mode 100644
index 00000000..139d726f
--- /dev/null
+++ b/crates/shirabe-symfony-string/src/lib.rs
@@ -0,0 +1,17 @@
+pub mod byte_string;
+pub mod code_point_string;
+pub mod unicode_string;
+
+pub use byte_string::*;
+pub use code_point_string::*;
+pub use unicode_string::*;
+
+/// Mirror of Symfony's `b()` helper function.
+pub fn b(string: &str) -> ByteString {
+    ByteString::new(string)
+}
+
+/// Mirror of Symfony's `u()` helper function.
+pub fn s(string: &str) -> UnicodeString {
+    UnicodeString::new(string)
+}