Rename tui_app_server to tui (#16104)

This is a follow-up to https://github.com/openai/codex/pull/15922. That
previous PR deleted the old `tui` directory and left the new
`tui_app_server` directory in place. This PR renames `tui_app_server` to
`tui` and fixes up all references.

codex-rs/tui/tests/suite/status_indicator.rs

@@ -0,0 +1,24 @@
+//! Regression test: ensure that `StatusIndicatorWidget` sanitises ANSI escape
+//! sequences so that no raw `\x1b` bytes are written into the backing
+//! buffer.  Rendering logic is tricky to unit‑test end‑to‑end, therefore we
+//! verify the *public* contract of `ansi_escape_line()` which the widget now
+//! relies on.
+
+use codex_ansi_escape::ansi_escape_line;
+
+#[test]
+fn ansi_escape_line_strips_escape_sequences() {
+    let text_in_ansi_red = "\x1b[31mRED\x1b[0m";
+
+    // The returned line must contain three printable glyphs and **no** raw
+    // escape bytes.
+    let line = ansi_escape_line(text_in_ansi_red);
+
+    let combined: String = line
+        .spans
+        .iter()
+        .map(|span| span.content.to_string())
+        .collect();
+
+    assert_eq!(combined, "RED");
+}