all: delete the code nothing calls

From the audit (#5178). Each was unreachable from every client:

- Checklist add-item and delete-item: REST POST /items and DELETE /items/<id>,
  the Tauri commands, the store, rest and local adapters, the core's
  add_item/delete_item, set_item_text and remove_item, and the FFI exports.
  Adding, rewording and removing an item are body edits in every editor. The
  checked toggle stays, and its rewriter is simpler without the drop branch.
- Manual unfurl: POST /unfurl and its adapters. Previews arrive in the
  background after a save (unfurl_queue).
- The /api/config `android_client` key, android_release() and the
  APK_NAME/MANIFEST_NAME aliases. Phones poll /api/client/android.
- users.email_verified and users.avatar_path (migration 0037). Nothing set
  the first or read the second; the SMTP reset never checked verification.
- derive::extract_tags (only tests used it; the shared fixture now runs
  through extract_tag_spans), the unused check and link icons, and the
  unused editor_add_item string.
- The blob scheme is renamed tsblob -> inkblob. URLs are built as notes are
  read, so nothing stored carries the old one.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/adapters/local.ts

@@ -4,7 +4,7 @@
 //
 // Argument keys are camelCase; Tauri converts them to the Rust commands' snake_case
 // parameters (e.g. labelIds -> label_ids). A few operations have no offline meaning
-// yet (account auth, device linking, URL unfurl) — those reject with a clear message
+// yet (account auth, device linking) — those reject with a clear message
 // rather than silently failing; the board, editor, attachments, capture, filters,
 // labels, checklists, reminders, import and export all work fully offline.
 
@@ -55,9 +55,7 @@ export const local: Repo = {
     completeReminder: (id) => invoke<Note>("notes_complete_reminder", { id }),
     snoozeReminder: (id, minutes) => invoke<Note>("notes_snooze_reminder", { id, minutes }),
     setLabels: (id, labelIds) => invoke<Note>("notes_set_labels", { id, labelIds }),
-    addItem: (id, text) => invoke<Note>("notes_add_item", { id, text }),
     updateItem: (id, itemId, changes) => invoke<Note>("notes_update_item", { id, itemId, changes }),
-    deleteItem: (id, itemId) => invoke<Note>("notes_delete_item", { id, itemId }),
     // Kept on this device and uploaded by the next sync once linked (#5168). The bytes
     // go as the raw IPC body; the name is percent-encoded because a header carries
     // only ASCII.
@@ -70,7 +68,6 @@ export const local: Repo = {
         },
       }),
     deleteAttachment: (id, attId) => invoke<Note>("notes_delete_attachment", { id, attId }),
-    unfurl: () => Promise.reject<Note>(new Error(NEEDS_SERVER)),
     deletePreview: (id, previewId) => invoke<Note>("notes_delete_preview", { id, previewId }),
     // The archive crosses as raw bytes, as an attachment does.
     import: async (file) => invoke<ImportResult>("notes_import", new Uint8Array(await file.arrayBuffer())),