feat: publication management with cover images, PDFs, and fruit images (story #04)

Full CRUD for publications; link fruits to publications; upload per-fruit
PDF descriptions and fruit images stored as BYTEA; fruit detail page shows
publication descriptions and images. ImageOverlayDrawer for cover thumbnail
full-size view.

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

frontend/src/stores/publicationStore.ts

@@ -0,0 +1,65 @@
+import { defineStore } from 'pinia'
+import { ref } from 'vue'
+import {
+  listPublications,
+  getPublication,
+  createPublication,
+  updatePublication,
+  deletePublication,
+  type Publication,
+  type PublicationWriteDTO,
+} from '../api/publications'
+
+export const usePublicationStore = defineStore('publication', () => {
+  const publications = ref<Publication[]>([])
+  const current = ref<Publication | null>(null)
+  const loading = ref(false)
+  const error = ref<string | null>(null)
+
+  async function fetchPublications() {
+    loading.value = true
+    error.value = null
+    try {
+      publications.value = await listPublications()
+    } catch (e) {
+      error.value = e instanceof Error ? e.message : 'unknown error'
+    } finally {
+      loading.value = false
+    }
+  }
+
+  async function fetchPublication(id: number) {
+    loading.value = true
+    error.value = null
+    try {
+      current.value = await getPublication(id)
+    } catch (e) {
+      error.value = e instanceof Error ? e.message : 'unknown error'
+      current.value = null
+    } finally {
+      loading.value = false
+    }
+  }
+
+  async function create(dto: PublicationWriteDTO): Promise<Publication> {
+    const pub = await createPublication(dto)
+    publications.value = [pub, ...publications.value]
+    return pub
+  }
+
+  async function update(id: number, dto: PublicationWriteDTO): Promise<Publication> {
+    const pub = await updatePublication(id, dto)
+    const idx = publications.value.findIndex((p) => p.id === id)
+    if (idx !== -1) publications.value[idx] = pub
+    if (current.value?.id === id) current.value = pub
+    return pub
+  }
+
+  async function remove(id: number) {
+    await deletePublication(id)
+    publications.value = publications.value.filter((p) => p.id !== id)
+    if (current.value?.id === id) current.value = null
+  }
+
+  return { publications, current, loading, error, fetchPublications, fetchPublication, create, update, remove }
+})