fix: handle full-width space in katakana-to-IPA conversion

stationapi/src/domain/ipa.rs

@@ -176,6 +176,8 @@ fn lookup_single(c: char) -> Option<Phoneme> {
         'ン' => return Some(Phoneme::MoraicNasal),
         'ッ' => return Some(Phoneme::Geminate),
         'ー' => return Some(Phoneme::LongVowel),
+        // 空白（全角・半角）はそのまま透過
+        '　' | ' ' => return Some(Phoneme::Regular(" ")),
         _ => return None,
     };
     Some(Phoneme::Regular(ipa))
@@ -588,4 +590,22 @@ mod tests {
         // ッキョ → kkʲo (only the base consonant 'k' is geminated, not 'kʲ')
         assert_eq!(ipa("ニッキョウ"), "ɲikkʲoː");
     }
+
+    #[test]
+    fn test_dokkyo_daigakumae_soka_matsubara() {
+        // Full-width space between words should be preserved
+        assert_eq!(
+            ipa("ドッキョウダイガクマエ　ソウカマツバラ"),
+            "dokkʲoːdaiɡakɯmae soːkamat͡sɯbaɾa"
+        );
+    }
+
+    #[test]
+    fn test_dokkyo_daigakumae_soka_matsubara_halfwidth() {
+        // Half-width (ASCII) space between words should also be accepted
+        assert_eq!(
+            ipa("ドッキョウダイガクマエ ソウカマツバラ"),
+            "dokkʲoːdaiɡakɯmae soːkamat͡sɯbaɾa"
+        );
+    }
 }