feat(quick-upload): generate better title from structured filename

titleFromFilename() mirrors the same four patterns as the frontend
parseFilename() utility. Dropzone uploads to Mueller_Hans_19650312.pdf
now land with title "Hans Mueller (12.03.1965)" instead of the raw
stripped filename.

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

backend/src/main/java/org/raddatz/familienarchiv/service/DocumentService.java

@@ -65,7 +65,7 @@ public class DocumentService {
             // New uploads from the drop zone always start as incomplete
             document = Document.builder()
                     .originalFilename(originalFilename)
-                    .title(stripExtension(originalFilename))
+                    .title(titleFromFilename(originalFilename))
                     .status(DocumentStatus.UPLOADED)
                     .metadataComplete(false)
                     .build();
@@ -356,6 +356,57 @@ public class DocumentService {
         return dot > 0 ? filename.substring(0, dot) : filename;
     }
 
+    /**
+     * Derives a human-readable title from a structured filename.
+     * Supports patterns (full match only):
+     *   YYYY-MM-DD_Lastname_Firstname.ext
+     *   YYYYMMDD_Lastname_Firstname.ext
+     *   Lastname_Firstname_YYYY-MM-DD.ext
+     *   Lastname_Firstname_YYYYMMDD.ext
+     * Falls back to stripExtension for unrecognised names.
+     */
+    private static final java.util.regex.Pattern FN_DATE_ISO_NAME =
+        java.util.regex.Pattern.compile("^(\\d{4}-\\d{2}-\\d{2})_(\\p{L}+)_(\\p{L}+)\\.[^.]+$");
+    private static final java.util.regex.Pattern FN_DATE_COMPACT_NAME =
+        java.util.regex.Pattern.compile("^(\\d{8})_(\\p{L}+)_(\\p{L}+)\\.[^.]+$");
+    private static final java.util.regex.Pattern FN_NAME_DATE_ISO =
+        java.util.regex.Pattern.compile("^(\\p{L}+)_(\\p{L}+)_(\\d{4}-\\d{2}-\\d{2})\\.[^.]+$");
+    private static final java.util.regex.Pattern FN_NAME_DATE_COMPACT =
+        java.util.regex.Pattern.compile("^(\\p{L}+)_(\\p{L}+)_(\\d{8})\\.[^.]+$");
+
+    static String titleFromFilename(String filename) {
+        if (filename == null) return null;
+        java.util.regex.Matcher m;
+        String dateIso, lastName, firstName;
+
+        if ((m = FN_DATE_ISO_NAME.matcher(filename)).matches()) {
+            dateIso = m.group(1);
+            lastName = m.group(2);
+            firstName = m.group(3);
+        } else if ((m = FN_DATE_COMPACT_NAME.matcher(filename)).matches()) {
+            String compact = m.group(1);
+            dateIso = compact.substring(0, 4) + "-" + compact.substring(4, 6) + "-" + compact.substring(6, 8);
+            lastName = m.group(2);
+            firstName = m.group(3);
+        } else if ((m = FN_NAME_DATE_ISO.matcher(filename)).matches()) {
+            lastName = m.group(1);
+            firstName = m.group(2);
+            dateIso = m.group(3);
+        } else if ((m = FN_NAME_DATE_COMPACT.matcher(filename)).matches()) {
+            lastName = m.group(1);
+            firstName = m.group(2);
+            String compact = m.group(3);
+            dateIso = compact.substring(0, 4) + "-" + compact.substring(4, 6) + "-" + compact.substring(6, 8);
+        } else {
+            return stripExtension(filename);
+        }
+
+        // Format date as DD.MM.YYYY for the title
+        LocalDate date = LocalDate.parse(dateIso);
+        String dateDisplay = String.format("%02d.%02d.%d", date.getDayOfMonth(), date.getMonthValue(), date.getYear());
+        return firstName + " " + lastName + " (" + dateDisplay + ")";
+    }
+
     private static String sha256Hex(byte[] bytes) {
         try {
             MessageDigest digest = MessageDigest.getInstance("SHA-256");

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

@@ -518,4 +518,40 @@ class DocumentServiceTest {
 
         assertThat(count).isEqualTo(2);
     }
+
+    // ─── titleFromFilename ────────────────────────────────────────────────────
+
+    @Test
+    void titleFromFilename_dateIso_name() {
+        assertThat(DocumentService.titleFromFilename("1965-03-12_Mueller_Hans.pdf"))
+                .isEqualTo("Hans Mueller (12.03.1965)");
+    }
+
+    @Test
+    void titleFromFilename_dateCompact_name() {
+        assertThat(DocumentService.titleFromFilename("19650312_Mueller_Hans.pdf"))
+                .isEqualTo("Hans Mueller (12.03.1965)");
+    }
+
+    @Test
+    void titleFromFilename_name_dateIso() {
+        assertThat(DocumentService.titleFromFilename("Mueller_Hans_1965-03-12.pdf"))
+                .isEqualTo("Hans Mueller (12.03.1965)");
+    }
+
+    @Test
+    void titleFromFilename_name_dateCompact() {
+        assertThat(DocumentService.titleFromFilename("Mueller_Hans_19650312.pdf"))
+                .isEqualTo("Hans Mueller (12.03.1965)");
+    }
+
+    @Test
+    void titleFromFilename_fallsBackToStripExtension() {
+        assertThat(DocumentService.titleFromFilename("scan_001.pdf")).isEqualTo("scan_001");
+    }
+
+    @Test
+    void titleFromFilename_null_returnsNull() {
+        assertThat(DocumentService.titleFromFilename(null)).isNull();
+    }
 }