fix: configure blockchain node to start HTTP RPC server on port 8006

Fixed blockchain node HTTP RPC server not responding to requests by:
- Updated wrapper script to use combined_main.py instead of main.py
- Updated combined_main.py to use port 8006 for HTTP RPC server
- combined_main.py runs both blockchain node logic and HTTP RPC server together

Root cause:
- aitbc_chain.main only runs blockchain node logic (block production, gossip)
- HTTP RPC server was not being started
- Separate uvicorn process on port 8006 was hung/not responding

Solution:
- Use combined_main.py which starts both node and HTTP RPC server
- Configure HTTP RPC to run on port 8006 (not 8005 to avoid conflict with AI service)
- Blockchain node HTTP RPC now responds correctly on port 8006

This fixes the training script wallet balance timeout errors.

scripts/wrappers/aitbc-blockchain-node-wrapper.py

@@ -22,9 +22,10 @@ os.environ["DATA_DIR"] = str(DATA_DIR)
 os.environ["LOG_DIR"] = str(LOG_DIR)
 
 # Execute the actual service
+# Use combined_main to run both blockchain node and HTTP RPC server
 exec_cmd = [
     "/opt/aitbc/venv/bin/python",
     "-m",
-    "aitbc_chain.main"
+    "aitbc_chain.combined_main"
 ]
 os.execvp(exec_cmd[0], exec_cmd)