fix(ui): shorten install/uninstall/update timeouts for async RPCs

With the backend flipped to async-spawn, install/uninstall/update return
immediately with a { status, package_id } envelope. Client timeouts of
45m/11m were a leftover from synchronous handlers and masked real RPC
failures.

Drop all install/uninstall/update RPC timeouts to 15s. Progress and
terminal state still arrive through the live state stream — the RPC
only needs to confirm the spawn was accepted.

Return-type annotations updated in rpc-client.ts and stores/server.ts.
Five direct rpcClient.call sites across Marketplace.vue, Discover.vue,
and MarketplaceAppDetails.vue updated with the shorter timeout.

neode-ui/src/views/Discover.vue

@@ -489,7 +489,7 @@ async function installApp(app: MarketplaceApp) {
   try {
     const installUrl = app.url || app.manifestUrl || app.s9pkUrl
     installingApps.set(app.id, { ...installingApps.get(app.id)!, status: 'downloading', progress: 30, message: 'Downloading package...' })
-    await rpcClient.call({ method: 'package.install', params: { id: app.id, url: installUrl, version: app.version } })
+    await rpcClient.call({ method: 'package.install', params: { id: app.id, url: installUrl, version: app.version }, timeout: 15000 })
     installingApps.set(app.id, { ...installingApps.get(app.id)!, status: 'installing', progress: 60, message: 'Installing package...' })
     startInstallPolling(app.id, 'Starting application...')
   } catch (err) {
@@ -511,7 +511,7 @@ async function installCommunityApp(app: MarketplaceApp) {
     if ((app as Record<string, unknown>).containerConfig) {
       installParams.containerConfig = (app as Record<string, unknown>).containerConfig
     }
-    await rpcClient.call({ method: 'package.install', params: installParams, timeout: 180000 })
+    await rpcClient.call({ method: 'package.install', params: installParams, timeout: 15000 })
     installingApps.set(app.id, { ...installingApps.get(app.id)!, status: 'installing', progress: 60, message: 'Starting container...' })
     startInstallPolling(app.id, 'Initializing application...')
   } catch (err) {