feat: show forked from session id in /status (#9330)

Summary:
- Add forked_from to SessionMeta/SessionConfiguredEvent and persist it
for forked sessions.
- Surface forked_from in /status for tui + tui2 and add snapshots.

codex-rs/app-server/tests/common/rollout.rs

@@ -52,6 +52,7 @@ pub fn create_fake_rollout(
     // Build JSONL lines
     let meta = SessionMeta {
         id: conversation_id,
+        forked_from_id: None,
         timestamp: meta_rfc3339.to_string(),
         cwd: PathBuf::from("/"),
         originator: "codex".to_string(),
@@ -129,6 +130,7 @@ pub fn create_fake_rollout_with_text_elements(
     // Build JSONL lines
     let meta = SessionMeta {
         id: conversation_id,
+        forked_from_id: None,
         timestamp: meta_rfc3339.to_string(),
         cwd: PathBuf::from("/"),
         originator: "codex".to_string(),