feat: persistent app install state across navigation (#9)

Move installingApps from local refs in Marketplace/Discover to the
global server store. Install progress now persists when navigating
between views. My Apps shows installing overlay with progress bar
for apps being installed from the Marketplace.

Changes:
- server.ts: add installingApps Map + helpers to store
- Marketplace.vue: use store's installingApps instead of local ref
- Discover.vue: same
- Apps.vue: pass isInstalling + installProgress to AppCard
- AppCard.vue: add amber installing overlay with progress bar

522 tests pass, vue-tsc clean.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

neode-ui/src/stores/server.ts

@@ -1,13 +1,37 @@
 // Server store — computed server state and RPC action proxies
 
 import { defineStore } from 'pinia'
-import { computed } from 'vue'
+import { computed, ref } from 'vue'
 import { rpcClient } from '../api/rpc-client'
 import { useSyncStore } from './sync'
+import type { InstallProgress } from '../views/marketplace/marketplaceData'
 
 export const useServerStore = defineStore('server', () => {
   const sync = useSyncStore()
 
+  // Global install tracking — persists across navigation
+  const installingApps = ref<Map<string, InstallProgress>>(new Map())
+
+  function setInstallProgress(appId: string, progress: Partial<InstallProgress> & { id: string; title: string }) {
+    const existing = installingApps.value.get(appId)
+    installingApps.value.set(appId, {
+      status: 'downloading',
+      progress: 0,
+      message: 'Preparing...',
+      attempt: 0,
+      ...existing,
+      ...progress,
+    })
+  }
+
+  function clearInstallProgress(appId: string) {
+    installingApps.value.delete(appId)
+  }
+
+  function isInstalling(appId: string): boolean {
+    return installingApps.value.has(appId)
+  }
+
   // Computed — derived from sync store's data
   const serverName = computed(() => sync.serverInfo?.name || 'Archipelago')
   const isRestarting = computed(() => sync.serverInfo?.['status-info']?.restarting || false)
@@ -70,6 +94,12 @@ export const useServerStore = defineStore('server', () => {
     isShuttingDown,
     isOffline,
 
+    // Install tracking (global, persists across navigation)
+    installingApps,
+    setInstallProgress,
+    clearInstallProgress,
+    isInstalling,
+
     // Actions
     installPackage,
     uninstallPackage,