[tui] add optional details to TUI status header (#8293)

### What

Add optional `details` field to TUI's status indicator header. `details`
is shown under the header with text wrapping and a max height of 3
lines.

Duplicated changes to `tui2`.

### Why

Groundwork for displaying error details under `Reconnecting...` for
clarity with retryable errors.

Basic examples
<img width="1012" height="326" alt="image"
src="https://github.com/user-attachments/assets/dd751ceb-b179-4fb2-8fd1-e4784d6366fb"
/>

<img width="1526" height="358" alt="image"
src="https://github.com/user-attachments/assets/bbe466fc-faff-4a78-af7f-3073ccdd8e34"
/>

Truncation example
<img width="936" height="189" alt="image"
src="https://github.com/user-attachments/assets/f3f1b5dd-9050-438b-bb07-bd833c03e889"
/>

### Tests
Tested locally, added tests for truncation.

codex-rs/tui/src/text_formatting.rs

@@ -2,6 +2,18 @@ use unicode_segmentation::UnicodeSegmentation;
 use unicode_width::UnicodeWidthChar;
 use unicode_width::UnicodeWidthStr;
 
+pub(crate) fn capitalize_first(input: &str) -> String {
+    let mut chars = input.chars();
+    match chars.next() {
+        Some(first) => {
+            let mut capitalized = first.to_uppercase().collect::<String>();
+            capitalized.push_str(chars.as_str());
+            capitalized
+        }
+        None => String::new(),
+    }
+}
+
 /// Truncate a tool result to fit within the given height and width. If the text is valid JSON, we format it in a compact way before truncating.
 /// This is a best-effort approach that may not work perfectly for text where 1 grapheme is rendered as multiple terminal cells.
 pub(crate) fn format_and_truncate_tool_result(