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>

core/src/sync/blobs.rs

@@ -104,8 +104,9 @@ impl BlobStore {
 // store. The webview then caches and range-requests them like any other resource,
 // which a `data:` URI would have thrown away.
 
-/// The scheme the webview fetches attachment bytes over.
-pub const BLOB_SCHEME: &str = "tsblob";
+/// The scheme the webview fetches attachment bytes over. Nothing stores a URL built
+/// on it — `url_for` runs as each note is read — so renaming it costs nothing.
+pub const BLOB_SCHEME: &str = "inkblob";
 
 /// The blob directory, published once the app has resolved its data dir.
 ///
@@ -279,9 +280,9 @@ mod tests {
         // The platform split is the whole risk of this feature, and CI is headless,
         // so at least pin that the right branch was taken for THIS build.
         if cfg!(any(windows, target_os = "android")) {
-            assert!(url.starts_with("http://tsblob.localhost/"), "{url}");
+            assert!(url.starts_with("http://inkblob.localhost/"), "{url}");
         } else {
-            assert!(url.starts_with("tsblob://localhost/"), "{url}");
+            assert!(url.starts_with("inkblob://localhost/"), "{url}");
         }
     }