feat: enqueue streams in running player

Sources/App/StreamQueue.swift

@@ -18,6 +18,26 @@ struct StreamQueue: Sendable {
     private struct InvalidQueue: LocalizedError {
         var errorDescription: String? { "Invalid stream queue: expected version 1, 1–4096 unique supported videos and new absolute report files in private owned directories." }
     }
+    // Explicit-app URL delivery reaches both cold launches and already running players.
+    static func enqueueURL(for file: URL) -> URL {
+        var components = URLComponents()
+        components.scheme = "terebi-enqueue"
+        components.host = "queue"
+        components.queryItems = [URLQueryItem(name: "file", value: file.path)]
+        return components.url!
+    }
+
+    static func enqueueFile(from url: URL) throws -> URL {
+        guard let components = URLComponents(url: url, resolvingAgainstBaseURL: false),
+              components.scheme == "terebi-enqueue", components.host == "queue",
+              components.path.isEmpty, components.user == nil, components.password == nil,
+              components.port == nil, components.fragment == nil,
+              let query = components.queryItems, query.count == 1, query[0].name == "file",
+              let path = query[0].value, path.hasPrefix("/"), !path.contains("\0") else {
+            throw InvalidQueue()
+        }
+        return URL(fileURLWithPath: path).standardizedFileURL
+    }
 
     static func load(from file: URL) throws -> StreamQueue {
         do {