feat: validate config on startup, prompt setup wizard if fields missing

On REPL start, check for missing provider.apiKey, provider.baseUrl,
and subagentModel. Print a warning with instructions to run `claw setup`
or `/setup` if any are absent.

Co-authored-by: GLM 5.1 FP8 via Crush <crush@charm.land>

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

@@ -7086,6 +7086,29 @@ fn run_repl(
     println!("{}", cli.startup_banner());
     println!("{}", format_connected_line(&cli.model));
 
+    // Validate key config fields and prompt setup wizard if missing
+    {
+        let cwd = std::env::current_dir().unwrap_or_default();
+        if let Ok(config) = runtime::ConfigLoader::default_for(&cwd).load() {
+            let mut missing: Vec<&str> = Vec::new();
+            if config.provider().api_key().is_none() {
+                missing.push("provider.apiKey");
+            }
+            if config.provider().base_url().is_none() {
+                missing.push("provider.baseUrl");
+            }
+            if config.subagent_model().is_none() {
+                missing.push("subagentModel");
+            }
+            if !missing.is_empty() {
+                eprintln!("
+  Warning: Missing config fields: {}", missing.join(", "));
+                eprintln!("  Run claw setup or type /setup to configure.
+");
+            }
+        }
+    }
+
     // Discover and register LSP servers
     let lsp_servers = runtime::lsp_discovery::discover_available_servers();
     if !lsp_servers.is_empty() {