docs: add Mastra Agents integration documentation

- Included Mastra Agents in the integrations list in docs.json.
- Added a new card for Mastra Agents in the agents.mdx documentation with relevant details.

Author: sambharia

docs.json

@@ -437,6 +437,7 @@
                   "integrations/agents/langgraph",
                   "integrations/agents/livekit",
                   "integrations/agents/llama-agents",
+                  "integrations/agents/mastra-agents",
                   "integrations/agents/openai-swarm",
                   "integrations/agents/pydantic-ai",
                   "integrations/agents/phidata",

integrations/agents.mdx

@@ -44,6 +44,12 @@ description: "Portkey helps bring your agents to production"
     </Frame>
   </Card>
 
+  <Card title="Mastra Agents" href="/integrations/agents/mastra-agents">
+    <Frame>
+      <img src="/images/autogen/bya.avif" alt="Mastra Agents" />
+    </Frame>
+  </Card>
+
   <Card title="Llama Index" href="/integrations/agents/llama-agents">
     <Frame>
     <img src="/images/autogen/llama-a.jpg" alt="Llama Index" />