rework message styling (#2877)

https://github.com/user-attachments/assets/cf07f62b-1895-44bb-b9c3-7a12032eb371

codex-rs/tui/Cargo.toml

@@ -49,6 +49,7 @@ image = { version = "^0.25.6", default-features = false, features = [
     "jpeg",
     "png",
 ] }
+itertools = "0.14.0"
 lazy_static = "1"
 mcp-types = { path = "../mcp-types" }
 once_cell = "1"
@@ -87,6 +88,7 @@ unicode-segmentation = "1.12.0"
 unicode-width = "0.1"
 url = "2"
 uuid = "1"
+pathdiff = "0.2"
 
 [target.'cfg(unix)'.dependencies]
 libc = "0.2"