feat(agent): maxSteps configurable, défaut 8->24 (tâches multi-outils) (v0.37.0)

Construire un workflow n8n (flux SDK) dépasse 8 étapes. maxAgentSteps via
CHLOVA_MAX_AGENT_STEPS, passé config -> ChatService -> runAgentTurn. 83 tests
verts.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016w5jRe87MGdd6AMvXQcHNi

orchestrator/src/agent/chat-service.ts

@@ -20,6 +20,8 @@ export interface ChatServiceDeps {
   systemPrompt: string;
   logger: Logger;
   store?: ConversationStore;
+  /** Plafond d'étapes par tour (multi-outils). Défaut runAgentTurn sinon. */
+  maxSteps?: number;
 }
 
 export interface ChatResult {
@@ -75,6 +77,7 @@ export class ChatService {
       actor,
       guard: this.deps.guard,
       logger: this.deps.logger,
+      ...(this.deps.maxSteps ? { maxSteps: this.deps.maxSteps } : {}),
     });
     this.deps.logger.info({ actor, steps }, "tour d'agent terminé");
     return reply;