Feature Request: Add Nirium Protocol On-Chain Audit & IPFS Receipt Handler

### 🛡️ Feature Proposal: Immutable IPFS & On-Chain Audit Anchoring via Nirium Protocol

Hi AgentOps team!

We would love to contribute a native integration handler for **Nirium Protocol** (https://nirium.xyz).

#### What this adds:
It allows AgentOps users to automatically anchor agent execution receipts and LLM cost traces directly to IPFS and Stellar Mainnet/Testnet as cryptographically signed SHA-256 records.

#### Proposed Implementation (`agentops/partners/nirium_audit_handler.py`):
```python
import requests
from typing import Dict, Any

class NiriumAuditHandler:
"""
AgentOps integration that automatically anchors agent execution logs
to IPFS and Stellar Mainnet/Testnet via Nirium's Audit Trail API.
"""
def __init__(self, api_key: str, agent_id: str = "agentops_tracker"):
self.api_key = api_key
self.agent_id = agent_id
self.nirium_url = "https://nirium-agent.fly.dev/api/audit/log"

def record_event(self, event_name: str, payload: Dict[str, Any]) -> Dict[str, Any]:
"""Anchors an agent event hash directly on-chain."""
headers = {
"Authorization": f"Bearer {self.api_key}",
"Content-Type": "application/json"
}
body = {
"app_id": "agentops",
"event": event_name,
"payload": payload
}
response = requests.post(self.nirium_url, json=body, headers=headers)
return response.json()