Cache on server feature

Server will download video from supported players and add as raw video to playlist (only youtube is supported for now).

Cache for YT player is available after installing optional dependencies, see readme. For cache size see `cacheStorageLimitGiB ` in config.

There is also minor ux improvement, latest checkbox states will be keeped in local storage now.

README.md

@@ -23,7 +23,7 @@ Default channel example: https://synctube.onrender.com/
 
 ### Setup
 - Open `4200` port in your router settings (port is customizable)
-- `npm install ws` in this project folder ([NodeJS 14+](https://nodejs.org) required)
+- `npm ci` in this project folder ([NodeJS 14+](https://nodejs.org) required)
 - Run `node build/server.js`
 - Open showed "Local" link for yourself and send "Global" link to friends
 
@@ -42,6 +42,14 @@ or
 
 - (Docker container hides real local/global ips, so you need to checkout it manually)
 
+
+### Optional dependencies
+If you want to enable `Cache on server` feature for Youtube player, you can also run:
+```shell
+npm i @distube/ytdl-core@latest
+```
+And install `ffmpeg` on your server system. Default cache size is 3.0 GiB.
+
 ### Configuration
 It's just works, but you can also check [user/ folder](/user/README.md) for server settings and additional customization.
 

default-config.json

@@ -13,6 +13,7 @@
 	"templateUrl": "https://youtube.com/playlist?list=PL9FiZUDVMu9tc_85frYognMOVFC_-VkSX",
 	"youtubeApiKey": "AIzaSyDTk1OPRI9cDkAK_BKsBcv10DQCHse-QaA",
 	"youtubePlaylistLimit": 50,
+	"cacheStorageLimitGiB": 3.0,
 	"permissions": {
 		"banned": [],
 		"guest": ["writeChat", "addVideo", "removeVideo", "changeOrder", "toggleItemType", "requestLeader", "rewind"],