Show exec output on success with trimmed display (#4113)

- Refactor Exec Cell into its own module
- update exec command rendering to inline the first command line
- limit continuation lines
- always show trimmed output

codex-rs/tui/src/chatwidget/snapshots/codex_tui__chatwidget__tests__binary_size_ideal_response.snap

@@ -17,11 +17,15 @@ expression: visible_after
   through crates for heavy dependencies in Cargo.toml, including cli, core,
   exec, linux-sandbox, tui, login, ollama, and mcp.
 
-• Ran
-  └ for d in ansi-escape apply-patch arg0 cli common core exec execpolicy
-        file-search linux-sandbox login mcp-client mcp-server mcp-types ollama
-        tui; do echo "--- $d/Cargo.toml"; sed -n '1,200p' $d/Cargo.toml; echo;
-        done
+• Ran for d in ansi-escape apply-patch arg0 cli common core exec execpolicy
+  │ file-search linux-sandbox login mcp-client mcp-server mcp-types ollama
+  │ tui; do echo "--- $d/Cargo.toml"; sed -n '1,200p' $d/Cargo.toml; echo;
+  │ … +1 lines
+  └ --- ansi-escape/Cargo.toml
+    [package]
+    … +7 lines
+    ] }
+    tracing = { version
 
 • Explored
   └ Read Cargo.toml