feat(downloads): warn about Android background restrictions

lib/i18n/en.i18n.json

@@ -1206,7 +1206,35 @@
     "syncRuleSignInRequired": "Sign in required",
     "syncRuleNotAvailableForProfile": "Not available for current profile",
     "syncRuleUnknownServer": "Unknown server",
-    "syncRuleListCreated": "Sync rule created"
+    "syncRuleListCreated": "Sync rule created",
+    "backgroundWarning": {
+      "bannerBlocked": "Downloads will stop when you leave the app",
+      "bannerDegraded": "Background downloads may be limited",
+      "bannerAction": "Details",
+      "sheetTitle": "Background downloads are blocked",
+      "sheetTitleDegraded": "Background downloads may be limited",
+      "sheetIntro": "Android is preventing Plezy from downloading reliably in the background.",
+      "sheetIntroDegraded": "Your device is limiting when Plezy can download in the background.",
+      "reasonBackgroundRestricted": "Plezy's background usage is restricted. Set its battery or background usage to \"Unrestricted\".",
+      "reasonStandbyRestricted": "Android has put Plezy in a restricted standby state. Set its battery usage to \"Unrestricted\".",
+      "reasonDownloadChannelBlocked": "Download notifications are turned off, so progress and controls may be unavailable.",
+      "reasonNotificationsDisabled": "Notifications are turned off. On Android 13 or newer, they are required for long background downloads.",
+      "reasonDataSaver": "Data Saver is on, which blocks background downloads on mobile data. Downloads should still run on Wi-Fi.",
+      "reasonOemUnknown": "Downloads repeatedly stopped while Plezy was in the background. Check Plezy's battery or background usage settings.",
+      "openSettings": "Open settings",
+      "stillNotWorking": "Device-specific help",
+      "stillNotWorkingDescription": "See steps for your device, or send a log from Settings › View Logs if the issue continues.",
+      "dialogTitle": "Downloads may not finish",
+      "dialogDownloadAnyway": "Download anyway",
+      "dialogFixFirst": "Fix this first",
+      "statusTile": "Background downloads",
+      "statusOk": "Allowed to run in the background",
+      "statusBlocked": "Blocked by system settings",
+      "statusDegraded": "Limited by system settings",
+      "statusUnknown": "Not checked yet",
+      "settingsUnavailable": "Couldn't open system settings on this device",
+      "linkUnavailable": "Couldn't open dontkillmyapp.com on this device"
+    }
   },
   "shaders": {
     "title": "Shaders",