fix(cli): /status JSON emits null model and correct session_id in resume mode

Two bugs in --output-format json --resume /status:

1. 'model' field emitted 'restored-session' (a run-mode label) instead of
   the actual model or null. Fixed: status_json_value now takes Option<&str>
   for model; resume path passes None; live REPL path passes Some(model).

2. 'session_id' extracted parent dir name ('sessions') instead of the file
   stem. Session files are session-<id>.jsonl directly under .claw/sessions/,
   not in a subdirectory. Fixed: extract file_stem() instead of
   parent().file_name().

159 CLI tests pass.

rust/crates/rusty-claude-cli/src/main.rs

@@ -2741,7 +2741,7 @@ fn run_resume_command(
                     &context,
                 )),
                 json: Some(status_json_value(
-                    "restored-session",
+                    None,
                     StatusUsage {
                         message_count: session.messages.len(),
                         turns: tracker.turns(),
@@ -5006,7 +5006,7 @@ fn print_status_snapshot(
         CliOutputFormat::Json => println!(
             "{}",
             serde_json::to_string_pretty(&status_json_value(
-                model,
+                Some(model),
                 usage,
                 permission_mode.as_str(),
                 &context,
@@ -5017,7 +5017,7 @@ fn print_status_snapshot(
 }
 
 fn status_json_value(
-    model: &str,
+    model: Option<&str>,
     usage: StatusUsage,
     permission_mode: &str,
     context: &StatusContext,
@@ -5046,9 +5046,9 @@ fn status_json_value(
             "untracked_files": context.git_summary.untracked_files,
             "session": context.session_path.as_ref().map_or_else(|| "live-repl".to_string(), |path| path.display().to_string()),
             "session_id": context.session_path.as_ref().and_then(|path| {
-                // Session files live under .claw/sessions/<session-id>/<file>.jsonl
-                // Extract the session-id directory component.
-                path.parent().and_then(|p| p.file_name()).map(|n| n.to_string_lossy().into_owned())
+                // Session files are named <session-id>.jsonl directly under
+                // .claw/sessions/. Extract the stem (drop the .jsonl extension).
+                path.file_stem().map(|n| n.to_string_lossy().into_owned())
             }),
             "loaded_config_files": context.loaded_config_files,
             "discovered_config_files": context.discovered_config_files,