Add a Zagros Asset Hub history indexer for the explorer host (#32)

The explorer at explorer.pezkuwichain.io needs transfer history for Zagros
Asset Hub. It runs on the explorer host next to its own archive node, so the
manifest points at 127.0.0.1:9955 and the compose file binds everything
locally with memory limits and no published ports.

deploy-vps now ignores these files: a change to the Zagros indexer must not
rebuild or restart the mainnet stack and its bots on the indexer host.

.github/workflows/deploy-vps.yml

@@ -2,6 +2,11 @@ name: Deploy to VPS
 on:
   push:
     branches: [main]
+    # The Zagros history indexer runs on the explorer host, not here.
+    paths-ignore:
+      - zagros-assethub.yaml
+      - docker-compose.zagros.yml
+      - ops/zagros/**
 
 concurrency:
   group: deploy-vps