Continuously forward Key to musicplayer on one subject

And remove any `input_introducer` markers to allow sections
like `Search` show the "clean" input stream

src/musicplayer.gleam

@@ -8,7 +8,6 @@ import musicplayer/ui/ui
 
 pub fn main() -> Nil {
   let input_keys_name: Name(Key) = process.new_name("input_keys")
-  let input_stream_name: Name(List(String)) = process.new_name("input_stream")
 
   // `input_inject` is created by name to allow the `input` process that
   // owns `read_input` to be able to register and receive from it,
@@ -17,20 +16,13 @@ pub fn main() -> Nil {
   let input_inject_name: Name(Key) = process.new_name("input_inject_keys")
 
   // TODO should input.new just return the inject_subject?
-  input.new(input_keys_name, input_stream_name, input_inject_name)
+  input.new(input_keys_name, input_inject_name)
 
   let assert Ok(ui) = ui.new()
   let assert Ok(mpv) = mpv.new()
 
   let exit = process.new_subject()
   let assert Ok(_) =
-    musicplayer.new(
-      ui,
-      mpv,
-      input_keys_name,
-      input_stream_name,
-      input_inject_name,
-      exit,
-    )
+    musicplayer.new(ui, mpv, input_keys_name, input_inject_name, exit)
   process.receive_forever(exit)
 }