rework message styling (#2877)

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

codex-rs/Cargo.lock

@@ -973,11 +973,13 @@ dependencies = [
  "diffy",
  "image",
  "insta",
+ "itertools 0.14.0",
  "lazy_static",
  "libc",
  "mcp-types",
  "once_cell",
  "path-clean",
+ "pathdiff",
  "pretty_assertions",
  "rand 0.9.2",
  "ratatui",
@@ -3377,6 +3379,12 @@ dependencies = [
  "once_cell",
 ]
 
+[[package]]
+name = "pathdiff"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "df94ce210e5bc13cb6651479fa48d14f601d9858cfe0467f43ae157023b938d3"
+
 [[package]]
 name = "percent-encoding"
 version = "2.3.1"