feat(integration) : extract Gitea/BookStack/Zimbra/Share front into module layer

LST-68 (2.6) front. Completes the Integration module and Phase 2.

- New frontend/modules/integration/ layer (auto-detected): services
  (gitea, bookstack, zimbra, share, share-settings) + their DTOs, and the
  useShareStatus composable.
- Consumers repointed to ~/modules/integration/...: admin tabs
  (Gitea/BookStack/Zimbra/Share), PM task sections (TaskGitSection,
  TaskBookStackLinks, TaskDocumentShareLinker), ProjectDrawer, TaskModal,
  pages/documents.vue, components/share/SharedFilePreview.vue.
- Admin tabs, SharedFilePreview and documents/admin pages stay at their
  location (only imports updated). i18n stays global.

nuxt build passes; all routes preserved.

frontend/modules/integration/services/dto/share.ts

@@ -0,0 +1,53 @@
+export type FileEntry = {
+    name: string
+    path: string
+    isDir: boolean
+    size: number
+    modifiedAt: number | null
+    mimeType: string
+}
+
+export type Breadcrumb = {
+    name: string
+    path: string
+}
+
+export type ShareBrowseResult = {
+    path: string
+    breadcrumb: Breadcrumb[]
+    entries: FileEntry[]
+}
+
+export type ShareSearchResult = {
+    query: string
+    entries: FileEntry[]
+}
+
+export type ShareStatus = {
+    enabled: boolean
+}
+
+export type ShareSettings = {
+    host: string | null
+    shareName: string | null
+    basePath: string | null
+    domain: string | null
+    username: string | null
+    enabled: boolean
+    hasPassword: boolean
+}
+
+export type ShareSettingsWrite = {
+    host: string | null
+    shareName: string | null
+    basePath: string | null
+    domain: string | null
+    username: string | null
+    password?: string | null
+    enabled: boolean
+}
+
+export type ShareTestResult = {
+    success: boolean
+    message: string | null
+}