test(parser): add regression and cross-feature interaction tests

Regression test confirms already-spaced dot names are not double-spaced.
Interaction test confirms // separator works with dot-compressed names.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/src/test/java/org/raddatz/familienarchiv/service/PersonNameParserTest.java

@@ -169,6 +169,19 @@ class PersonNameParserTest {
                 .containsExactly("Dr.Fr.Zarncke");
     }
 
+    @Test
+    void split_alreadySpacedDotName_noDoubleSpacing() {
+        PersonNameParser.SplitName result = PersonNameParser.split("Dr. Fr. Zarncke");
+        assertThat(result.firstName()).isEqualTo("Dr. Fr.");
+        assertThat(result.lastName()).isEqualTo("Zarncke");
+    }
+
+    @Test
+    void slashSeparator_combinedWithDotCompressed() {
+        assertThat(PersonNameParser.parseReceivers("E.Rockstroh//Dr.Fr.Zarncke"))
+                .containsExactly("E.Rockstroh", "Dr.Fr.Zarncke");
+    }
+
     // --- parseReceivers — shared last name with full-name part ─────────────────
 
     @Test