Python: Fix stale agent.json references in A2A sample (#7281)

Co-authored-by: Amit Dhawan <amit.dhawan@barco.com>

python/samples/04-hosting/a2a/a2a_server.http

@@ -4,7 +4,7 @@
 @hostLogistics = http://localhost:5002
 
 ### Query agent card for the invoice agent
-GET {{hostInvoice}}/.well-known/agent.json
+GET {{hostInvoice}}/.well-known/agent-card.json
 
 ### Send a message to the invoice agent
 POST {{hostInvoice}}
@@ -30,7 +30,7 @@ Content-Type: application/json
 }
 
 ### Query agent card for the policy agent
-GET {{hostPolicy}}/.well-known/agent.json
+GET {{hostPolicy}}/.well-known/agent-card.json
 
 ### Send a message to the policy agent
 POST {{hostPolicy}}
@@ -56,7 +56,7 @@ Content-Type: application/json
 }
 
 ### Query agent card for the logistics agent
-GET {{hostLogistics}}/.well-known/agent.json
+GET {{hostLogistics}}/.well-known/agent-card.json
 
 ### Send a message to the logistics agent
 POST {{hostLogistics}}

python/samples/04-hosting/a2a/a2a_server.py

@@ -36,7 +36,7 @@ A2A Server Sample — Host an Agent Framework agent as an A2A endpoint
 
 This sample creates a Python-based A2A-compliant server that wraps an Agent
 Framework agent.  The server uses the a2a-sdk's Starlette application to handle
-JSON-RPC requests and serves the AgentCard at /.well-known/agent.json.
+JSON-RPC requests and serves the AgentCard at /.well-known/agent-card.json.
 
 Three agent types are available:
   - invoice   — Answers invoice queries using mock data and function tools.
@@ -194,7 +194,7 @@ def main() -> None:
     print(f"Starting A2A server: {agent_card.name}")
     print(f"  Agent type : {args.agent_type}")
     print(f"  Listening  : {url}")
-    print(f"  Agent card : {url}.well-known/agent.json")
+    print(f"  Agent card : {url}.well-known/agent-card.json")
     print()
 
     uvicorn.run(