test(dates): pin edit-form precision field binding to DocumentUpdateDTO

@WebMvcTest multipart PUT asserting metaDatePrecision / metaDateEnd /
metaDateRaw form field names bind to the DTO. A rename on either side
silently drops the precision edit; the captured DTO catches it.

Refs #666
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/src/test/java/org/raddatz/familienarchiv/document/DocumentControllerTest.java

@@ -294,6 +294,34 @@ class DocumentControllerTest {
                 .andExpect(status().isOk());
     }
 
+    @Test
+    @WithMockUser(authorities = "WRITE_ALL")
+    void updateDocument_bindsPrecisionFormFields_toDTO() throws Exception {
+        // Pins the wire contract: the edit form's metaDatePrecision / metaDateEnd /
+        // metaDateRaw multipart field names must bind to DocumentUpdateDTO. A rename
+        // on either side silently drops the precision edit; this captures the DTO.
+        UUID id = UUID.randomUUID();
+        Document doc = Document.builder().id(id).title("Brief").originalFilename("brief.pdf").build();
+        when(userService.findByEmail(any())).thenReturn(AppUser.builder().id(UUID.randomUUID()).build());
+
+        org.mockito.ArgumentCaptor<DocumentUpdateDTO> captor =
+                org.mockito.ArgumentCaptor.forClass(DocumentUpdateDTO.class);
+        when(documentService.updateDocument(eq(id), captor.capture(), any(), any())).thenReturn(doc);
+
+        mockMvc.perform(multipart("/api/documents/" + id)
+                        .param("metaDatePrecision", "RANGE")
+                        .param("metaDateEnd", "1917-01-11")
+                        .param("metaDateRaw", "10.–11. Januar 1917")
+                        .with(req -> { req.setMethod("PUT"); return req; }).with(csrf()))
+                .andExpect(status().isOk());
+
+        DocumentUpdateDTO bound = captor.getValue();
+        org.assertj.core.api.Assertions.assertThat(bound.getMetaDatePrecision()).isEqualTo(DatePrecision.RANGE);
+        org.assertj.core.api.Assertions.assertThat(bound.getMetaDateEnd())
+                .isEqualTo(java.time.LocalDate.of(1917, 1, 11));
+        org.assertj.core.api.Assertions.assertThat(bound.getMetaDateRaw()).isEqualTo("10.–11. Januar 1917");
+    }
+
     // ─── DELETE /api/documents/{id} ──────────────────────────────────────────
 
     @Test