tui: switch to using tokio + EventStream for processing crossterm events (#2489)

bringing the tui more into tokio-land to make it easier to factorize.

fyi @bolinfest

codex-rs/tui/Cargo.toml

@@ -38,7 +38,7 @@ codex-login = { path = "../login" }
 codex-ollama = { path = "../ollama" }
 codex-protocol = { path = "../protocol" }
 color-eyre = "0.6.3"
-crossterm = { version = "0.28.1", features = ["bracketed-paste"] }
+crossterm = { version = "0.28.1", features = ["bracketed-paste", "event-stream"] }
 diffy = "0.4.2"
 image = { version = "^0.25.6", default-features = false, features = ["jpeg"] }
 lazy_static = "1"
@@ -68,6 +68,7 @@ tokio = { version = "1", features = [
     "rt-multi-thread",
     "signal",
 ] }
+tokio-stream = "0.1.17"
 tracing = { version = "0.1.41", features = ["log"] }
 tracing-appender = "0.2.3"
 tracing-subscriber = { version = "0.3.19", features = ["env-filter"] }