chore(systemd): remove obsolete systemd service files and update infrastructure documentation

- Remove 8 unused systemd service files from coordinator-api/systemd/
  - aitbc-adaptive-learning.service (port 8005)
  - aitbc-advanced-ai.service
  - aitbc-enterprise-api.service
  - aitbc-gpu-multimodal.service (port 8003)
  - aitbc-marketplace-enhanced.service (port 8006)
  - aitbc-modality-optimization.service (port 8004)
  - aitbc-multimodal.service (port 8002)
  - aitbc-openclaw-enhanced.service (port 8007

apps/blockchain-node/scripts/assign_proposer.py

@@ -0,0 +1,75 @@
+#!/usr/bin/env python3
+"""
+Script to assign a proposer to a block by polling for it
+"""
+
+import httpx
+import json
+
+# Configuration
+COORDINATOR_URL = "http://localhost:8001"
+MINER_API_KEY = "${MINER_API_KEY}"
+MINER_ID = "localhost-gpu-miner"
+
+def assign_proposer_to_latest_block():
+    """Poll for the latest unassigned job to become the proposer"""
+    
+    # First register the miner
+    print("📝 Registering miner...")
+    register_response = httpx.post(
+        f"{COORDINATOR_URL}/v1/miners/register?miner_id={MINER_ID}",
+        headers={
+            "Content-Type": "application/json",
+            "X-Api-Key": MINER_API_KEY
+        },
+        json={
+            "capabilities": {
+                "gpu": {"model": "RTX 4060 Ti", "memory_gb": 16}
+            }
+        }
+    )
+    
+    if register_response.status_code != 200:
+        print(f"❌ Registration failed: {register_response.text}")
+        return
+    
+    print("✅ Miner registered")
+    
+    # Poll for a job
+    print("\n🔍 Polling for jobs...")
+    poll_response = httpx.post(
+        f"{COORDINATOR_URL}/v1/miners/poll",
+        headers={
+            "Content-Type": "application/json",
+            "X-Api-Key": MINER_API_KEY
+        },
+        json={"max_wait_seconds": 1}
+    )
+    
+    if poll_response.status_code == 200:
+        job = poll_response.json()
+        print(f"✅ Received job: {job['job_id']}")
+        print(f"   This job is now assigned to miner: {MINER_ID}")
+        
+        # Check the block
+        print("\n📦 Checking block...")
+        blocks_response = httpx.get(f"{COORDINATOR_URL}/v1/explorer/blocks")
+        
+        if blocks_response.status_code == 200:
+            blocks = blocks_response.json()
+            for block in blocks['items']:
+                if block['hash'] == job['job_id']:
+                    print(f"✅ Block updated!")
+                    print(f"   Height: {block['height']}")
+                    print(f"   Hash: {block['hash']}")
+                    print(f"   Proposer: {block['proposer']}")
+                    break
+    elif poll_response.status_code == 204:
+        print("ℹ️  No jobs available to poll")
+    else:
+        print(f"❌ Poll failed: {poll_response.text}")
+
+if __name__ == "__main__":
+    print("🎯 Assign Proposer to Latest Block")
+    print("=" * 40)
+    assign_proposer_to_latest_block()