Add tsconfig.json to fix vite-plugin-dts crash during config load

@nextcloud/vite-config's index.js barrel statically re-exports
createLibConfig from libConfig.js, which imports vite-plugin-dts at
module scope. That import chain runs even though we only use
createAppConfig, and vite-plugin-dts crashes while resolving a
tsconfig that did not exist in this (plain JS/Vue) project.

tsconfig.json

@@ -0,0 +1,16 @@
+{
+	"compilerOptions": {
+		"target": "ES2022",
+		"module": "ESNext",
+		"moduleResolution": "Bundler",
+		"lib": ["ES2022", "DOM"],
+		"allowJs": true,
+		"checkJs": false,
+		"skipLibCheck": true,
+		"resolveJsonModule": true,
+		"isolatedModules": true,
+		"noEmit": true,
+		"strict": false
+	},
+	"include": ["src/**/*.js", "src/**/*.vue", "vite.config.js"]
+}