feat(geschichte): add DocumentSummary, JourneyItemView, GeschichteView read models

DocumentSummary: lean document projection for journey item embedding —
skips tag-color resolution (getSummaryById), includes receiverCount
(0 when no receivers, non-null). JourneyItemView: response record for
item CRUD and GET. GeschichteView: detail response with summarised
author {id, displayName} to prevent AppUser email/group leak.

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

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

@@ -1006,6 +1006,16 @@ public class DocumentService {
         return doc;
     }
 
+    /**
+     * Lean document lookup for embedding in JourneyItemView. Skips
+     * {@code tagService.resolveEffectiveColors} — ×N items per journey GET is wasted
+     * work that summary consumers never read. Called within a caller-provided transaction.
+     */
+    public Document getSummaryById(UUID id) {
+        return documentRepository.findById(id)
+                .orElseThrow(() -> DomainException.notFound(ErrorCode.DOCUMENT_NOT_FOUND, "Document not found: " + id));
+    }
+
     /**
      * Loads a document for the detail view, additionally flagging whether it has any
      * transcription to read. Kept separate from {@link #getDocumentById} so the cheap

backend/src/main/java/org/raddatz/familienarchiv/geschichte/DocumentSummary.java

@@ -0,0 +1,23 @@
+package org.raddatz.familienarchiv.geschichte;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+import org.raddatz.familienarchiv.document.DatePrecision;
+
+import java.time.LocalDate;
+import java.util.UUID;
+
+/**
+ * Lean read-model view of a Document for embedding in JourneyItemView.
+ * Built by JourneyItemService.toSummary(Document) — never serialised from
+ * a JPA entity to avoid LazyInitializationException and tag-color overhead.
+ */
+public record DocumentSummary(
+        @Schema(requiredMode = Schema.RequiredMode.REQUIRED) UUID id,
+        @Schema(requiredMode = Schema.RequiredMode.REQUIRED) String title,
+        LocalDate documentDate,
+        LocalDate documentDateEnd,
+        @Schema(requiredMode = Schema.RequiredMode.REQUIRED) DatePrecision datePrecision,
+        String senderName,
+        String receiverName,
+        @Schema(requiredMode = Schema.RequiredMode.REQUIRED) Integer receiverCount
+) {}

backend/src/main/java/org/raddatz/familienarchiv/geschichte/GeschichteView.java

@@ -0,0 +1,36 @@
+package org.raddatz.familienarchiv.geschichte;
+
+import com.fasterxml.jackson.annotation.JsonInclude;
+import io.swagger.v3.oas.annotations.media.Schema;
+import org.raddatz.familienarchiv.geschichte.journeyitem.JourneyItemView;
+import org.raddatz.familienarchiv.person.Person;
+
+import java.time.LocalDateTime;
+import java.util.List;
+import java.util.Set;
+import java.util.UUID;
+
+/**
+ * Detail-view response for GET /api/geschichten/{id}. Assembled by
+ * GeschichteService — never the raw entity (author AppUser graph must not leak).
+ * items is always present (both STORY and JOURNEY); empty list for stories with no items.
+ */
+public record GeschichteView(
+        @Schema(requiredMode = Schema.RequiredMode.REQUIRED) UUID id,
+        @Schema(requiredMode = Schema.RequiredMode.REQUIRED) String title,
+        String body,
+        @Schema(requiredMode = Schema.RequiredMode.REQUIRED) GeschichteStatus status,
+        @Schema(requiredMode = Schema.RequiredMode.REQUIRED) GeschichteType type,
+        AuthorView author,
+        @Schema(requiredMode = Schema.RequiredMode.REQUIRED) Set<Person> persons,
+        @Schema(requiredMode = Schema.RequiredMode.REQUIRED) List<JourneyItemView> items,
+        LocalDateTime publishedAt,
+        @Schema(requiredMode = Schema.RequiredMode.REQUIRED) LocalDateTime createdAt,
+        @Schema(requiredMode = Schema.RequiredMode.REQUIRED) LocalDateTime updatedAt
+) {
+    /** Summarised author — exposes only id and displayName, never email or group memberships. */
+    public record AuthorView(
+            @Schema(requiredMode = Schema.RequiredMode.REQUIRED) UUID id,
+            @Schema(requiredMode = Schema.RequiredMode.REQUIRED) String displayName
+    ) {}
+}

backend/src/main/java/org/raddatz/familienarchiv/geschichte/journeyitem/JourneyItemView.java

@@ -0,0 +1,17 @@
+package org.raddatz.familienarchiv.geschichte.journeyitem;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+import org.raddatz.familienarchiv.geschichte.DocumentSummary;
+
+import java.util.UUID;
+
+/**
+ * Read-model response for a JourneyItem. Never the JPA entity (which has a
+ * Geschichte back-reference that would leak / hit LazyInitializationException).
+ */
+public record JourneyItemView(
+        @Schema(requiredMode = Schema.RequiredMode.REQUIRED) UUID id,
+        @Schema(requiredMode = Schema.RequiredMode.REQUIRED) int position,
+        DocumentSummary document,
+        String note
+) {}