fix(blockchain): enable cross-node P2P with Broadcast backend

- Pin starlette to >=0.37.2,<0.38 to retain Broadcast module
- Add redis dependency for Broadcast transport
- Configure node to use broadcast gossip backend via Redis
- Update .env: gossip_backend=broadcast, gossip_broadcast_url=redis://localhost:6379
- Restarted node with clean DB; RPC on port 8005
- Fixed CLI blockchain_rpc_url via env
- Minted test funds via faucet

Closes #debug-services

apps/blockchain-node/pyproject.toml

@@ -26,6 +26,8 @@ rich = "^13.7.1"
 cryptography = "^46.0.5"
 asyncpg = ">=0.29.0"
 requests = "^2.32.5"
+# Pin starlette to a version with Broadcast (removed in 0.38)
+starlette = ">=0.37.2,<0.38.0"
 
 [tool.poetry.extras]
 uvloop = ["uvloop"]