refactor: 音素を列挙型で表現する

crates/voicevox_core/Cargo.toml

@@ -27,6 +27,7 @@ async-fs.workspace = true
 async-lock.workspace = true
 async_zip = { workspace = true, features = ["deflate"] }
 blocking.workspace = true
+bytemuck = { version = "1.24.0", features = ["derive"] }
 camino.workspace = true
 const_format.workspace = true
 derive-getters.workspace = true

crates/voicevox_core/src/engine.rs

@@ -6,4 +6,7 @@ mod mora_list;
 pub(crate) mod talk;
 
 pub use self::audio_file::wav_from_s16le;
-pub(crate) use self::{acoustic_feature_extractor::OjtPhoneme, audio_file::to_s16le_pcm};
+pub(crate) use self::{
+    acoustic_feature_extractor::{__phoneme_code, phoneme_codes, PhonemeCode},
+    audio_file::to_s16le_pcm,
+};