Restructure mpv/internal package

src/mpv/mpv.gleam

@@ -2,7 +2,7 @@ import gleam/erlang/process.{type Subject}
 import gleam/otp/actor
 import gleam/string
 
-import mpv/internal.{type Key, Char}
+import mpv/key.{type Key, Char}
 import tcp/reason.{type Reason}
 import tcp/tcp.{type Socket}
 
@@ -30,7 +30,7 @@ pub fn new(exit: Subject(Nil)) -> Result(Nil, String) {
           Error("Could not start actor: " <> string.inspect(start_error))
         Ok(actor.Started(data:, ..)) -> {
           echo "waiting for input"
-          internal.start_raw_shell()
+          key.start_raw_shell()
           process.spawn(fn() { read_input(data) })
           Ok(Nil)
         }
@@ -60,7 +60,7 @@ fn handle_message(
 }
 
 fn read_input(subject: Subject(Message)) -> Nil {
-  internal.read_input_until_key([]) |> KeyPress |> process.send(subject, _)
+  key.read_input_until_key([]) |> KeyPress |> process.send(subject, _)
 
   read_input(subject)
 }