feat: text normalization with medical abbreviation expansion

tests/normalize_tests.rs

@@ -0,0 +1,17 @@
+use alpha_id::normalize::normalize;
+
+#[test]
+fn lowercases_and_collapses_whitespace() {
+    assert_eq!(normalize("  Diabetes   Mellitus\tTyp 2 "), "diabetes mellitus typ 2");
+}
+
+#[test]
+fn expands_common_medical_abbreviations() {
+    assert_eq!(normalize("V.a. art. Hypertonie"), "verdacht auf arterielle hypertonie");
+    assert_eq!(normalize("Z.n. OP"), "zustand nach operation");
+}
+
+#[test]
+fn keeps_german_umlauts() {
+    assert_eq!(normalize("Ödem"), "ödem");
+}