Commit inicial: G Radio Remoto (gr-client)

Cliente remoto GTK4 para G Radio Player: se conecta al servidor TCP
embebido en radio-player para controlar el reproductor y editar
programación (pautaje, parrilla, botonera, buscador, reportes) desde
otra máquina de la LAN.

Cargo.toml

@@ -0,0 +1,35 @@
+[package]
+name = "radio-player-client"
+version = "0.1.7"
+edition = "2021"
+description = "G Radio Client — cliente remoto para G Radio Player"
+
+[[bin]]
+name = "gr-client"
+path = "src/main.rs"
+
+[dependencies]
+# GTK4 GUI
+gtk4      = { version = "0.9", features = ["v4_6", "v4_8"] }
+glib      = "0.20"
+glib-macros = "0.20"
+gdk4      = "0.9"
+gdk-pixbuf = "0.20"
+cairo-rs  = { version = "0.20", features = ["png"] }
+
+# Red / async
+tokio     = { version = "1", features = ["full"] }
+
+# Serialización
+serde     = { version = "1", features = ["derive"] }
+serde_json = "1"
+
+# Utilidades
+chrono    = { version = "0.4", features = ["clock"] }
+dirs      = "5"
+anyhow    = "1"
+log       = "0.4"
+env_logger = "0.11"
+tokio-tungstenite = { version = "0.24", features = ["native-tls"] }
+futures-util      = "0.3"
+native-tls        = "0.2"