release: publish v2.0.19 sidebar interaction fixes

Restore the shared sliding-selection transition after React StrictMode effect restarts, disable redundant service filters, add regression coverage, and update the public English changelog and package metadata for v2.0.19.

src/renderer/views/downloads/DownloadsView.tsx

@@ -88,7 +88,7 @@ export function DownloadsSidebar({ actions, model }: { actions: DownloadsViewAct
       <SlidingSelection activeKey={model.filter} aria-label="Downloadfilter" as="nav" axis="vertical">
         {filters.map((filter) => <button className={model.filter === filter.id ? "is-active" : ""} data-sliding-selection-active={model.filter === filter.id} data-sliding-selection-item="true" key={filter.id} onClick={() => actions.onFilterChange(filter.id)} type="button"><span>{filter.label}</span><b>{model.counts[filter.id]}</b></button>)}
       </SlidingSelection>
-      <label className="downloads-provider-filter"><span>Service</span><select aria-label="Service filtern" onChange={(event) => actions.onProviderFilterChange(event.target.value)} value={model.providerFilter}><option value="all">Alle Services</option>{model.providerOptions.map((provider) => <option key={provider.id} value={provider.id}>{provider.label}</option>)}</select></label>
+      <label className="downloads-provider-filter"><span>Service</span><select aria-label="Service filtern" disabled={model.providerOptions.length <= 1} onChange={(event) => actions.onProviderFilterChange(event.target.value)} value={model.providerFilter}><option value="all">Alle Services</option>{model.providerOptions.map((provider) => <option key={provider.id} value={provider.id}>{provider.label}</option>)}</select></label>
       <label className="downloads-sidebar-search"><span>Downloads durchsuchen</span><input className="downloads-search-input" onChange={(event) => actions.onQueryChange(event.target.value)} placeholder="Paket, Datei oder Service" type="search" value={model.query} /></label>
       <div className="downloads-sidebar-actions">
         <button onClick={actions.onToggleAllPackages} type="button">Alle ein-/ausklappen</button>