refactor: plugin system

backend/plugins/jellyfin.plugin/package-lock.json

@@ -12,9 +12,15 @@
         "@types/axios": "^0.14.4",
         "axios": "^1.7.8",
         "express-http-proxy": "^2.1.1",
+        "plugin-types": "file:../plugin-types",
         "swagger-typescript-api": "^13.0.23"
       }
     },
+    "../plugin-types": {
+      "version": "1.0.0",
+      "license": "ISC",
+      "devDependencies": {}
+    },
     "node_modules/@babel/code-frame": {
       "version": "7.26.2",
       "resolved": "https://registry.npmjs.org/@babel/code-frame/-/code-frame-7.26.2.tgz",
@@ -600,6 +606,10 @@
       "resolved": "https://registry.npmjs.org/picocolors/-/picocolors-1.1.1.tgz",
       "integrity": "sha512-xceH2snhtb5M9liqDsmEw56le376mTZkEX/jEb/RxNFyegNul7eNslCXP9FDj/Lcu0X8KEyMceP2ntpaHrDEVA=="
     },
+    "node_modules/plugin-types": {
+      "resolved": "../plugin-types",
+      "link": true
+    },
     "node_modules/prettier": {
       "version": "3.3.3",
       "resolved": "https://registry.npmjs.org/prettier/-/prettier-3.3.3.tgz",