fix: conditionally include tools field in session config only when tools are present

- Modified #getSessionConfig to only include tools field when #currentTools.length > 0
- Fixes failing test 'does not include tools field when no tools are provided'
- Preserves existing behavior for agents with actual tools

Author: AjayKumbham

packages/agents-realtime/src/realtimeSession.ts

@@ -340,10 +340,14 @@ export class RealtimeSession<
       // Use session config voice if provided, otherwise fall back to agent voice
       voice: base.voice ?? this.#currentAgent.voice,
       model: this.options.model,
-      tools: this.#currentTools,
       tracing: tracingConfig,
     };
 
+    // Only include tools field if there are actually tools
+    if (this.#currentTools.length > 0) {
+      fullConfig.tools = this.#currentTools;
+    }
+
     // Update our cache so subsequent updates inherit the full set including any
     // dynamic fields we just overwrote.
     this.#lastSessionConfig = fullConfig;