fix: change miner authentication to use separate X-Miner-ID header instead of API key for miner identification

- Add get_miner_id() dependency to extract miner ID from X-Miner-ID header
- Update miner register and heartbeat endpoints to require both X-Miner-ID and X-Api-Key headers
- Remove miner_id from query parameters in favor of header-based extraction
- Fix miner heartbeat CLI to send proper JSON payload with inflight, status, and metadata fields
- Fix typo in MinerService: extra_metadata → extra_meta_data

apps/coordinator-api/src/app/services/miners.py

@@ -54,7 +54,7 @@ class MinerService:
             metadata["edge_optimized"] = payload.edge_optimized
         if payload.network_latency_ms is not None:
             metadata["network_latency_ms"] = payload.network_latency_ms
-        miner.extra_metadata = metadata
+        miner.extra_meta_data = metadata
         miner.last_heartbeat = datetime.utcnow()
         self.session.add(miner)
         self.session.commit()