refactor: idiomatic find in primary_code (clippy)

src/corpus.rs

@@ -36,8 +36,8 @@ pub fn load(path: &str) -> Result<Vec<AlphaIdEntry>, AppError> {
 
 /// The primary ICD code a matched entry contributes (falls back to star/addon).
 pub fn primary_code(e: &AlphaIdEntry) -> Option<&str> {
-    for c in [&e.icd_primary, &e.icd_primary2, &e.icd_star, &e.icd_addon] {
+    [&e.icd_primary, &e.icd_primary2, &e.icd_star, &e.icd_addon]
-        if !c.is_empty() { return Some(c); }
+        .into_iter()
-    }
+        .find(|c| !c.is_empty())
-    None
+        .map(|s| s.as_str())
 }