Fix Store.add regression causing isLoaded to remain false

Problem

A recent change to Neo.data.Store (specifically the optimization to return early when init=true in add()) introduced a regression where me.isLoaded was not being set to true in the eager instantiation path.

Broken Code:

if (init) {
    super.add(items);
    return items.map(i => me.get(i[me.getKeyProperty()])) // isLoaded never set!
}

This caused components relying on isLoaded (like ComboBox during initial value resolution) to fail, as they perceived the store as unloaded even after data was added.

Solution

Ensure me.isLoaded = true is set in the eager instantiation path as well.

if (init) {
    super.add(items);
    me.isLoaded = true; // Fix
    return items.map(i => me.get(i[me.getKeyProperty()]))
}