feat(core,app,android,ios): rename a share

ShareStore::rename changes only the name; the id that the catalog, watch
state and offline files are keyed by stays the same. Sync carries the
change as it does any other change to the share's register. The desktop
renames in the share's row. The phones rename from the share's menu.
Before, the name given at add time was permanent short of removing the
share.

crates/pstr-app/src/engine.rs

@@ -696,6 +696,16 @@ impl Engine {
         });
     }
 
+    /// Call a share something else. See [`ShareStore::rename`].
+    pub fn rename_share(&self, id: String, name: String) {
+        let engine = self.clone();
+        self.runtime
+            .spawn_blocking(move || match engine.store.rename(&id, &name) {
+                Ok(_) => engine.load_shares(),
+                Err(error) => engine.fail("rename the share", error),
+            });
+    }
+
     /// Re-supply the link behind a share whose stored secret is unreadable —
     /// a keyring that was reset — or whose custom password changed, keeping
     /// its catalog, watch state and downloads. See