Add session loading support to Codex (#1602)

## Summary
- extend rollout format to store all session data in JSON
- add resume/write helpers for rollouts
- track session state after each conversation
- support `LoadSession` op to resume a previous rollout
- allow starting Codex with an existing session via
`experimental_resume` config variable

We need a way later for exploring the available sessions in a user
friendly way.

## Testing
- `cargo test --no-run` *(fails: `cargo: command not found`)*

------
https://chatgpt.com/codex/tasks/task_i_68792a29dd5c832190bf6930d3466fba

This video is outdated. you should use `-c experimental_resume:<full
path>` instead of `--resume <full path>`


https://github.com/user-attachments/assets/7a9975c7-aa04-4f4e-899a-9e87defd947a

codex-rs/common/src/config_override.rs

@@ -64,7 +64,11 @@ impl CliConfigOverrides {
                 // `-c model=o3` without the quotes.
                 let value: Value = match parse_toml_value(value_str) {
                     Ok(v) => v,
-                    Err(_) => Value::String(value_str.to_string()),
+                    Err(_) => {
+                        // Strip leading/trailing quotes if present
+                        let trimmed = value_str.trim().trim_matches(|c| c == '"' || c == '\'');
+                        Value::String(trimmed.to_string())
+                    }
                 };
 
                 Ok((key.to_string(), value))