pin bee to 2.7.1 — 2.8 handshake incompatible with mainnet

The latest tag (currently 2.8.0) speaks /swarm/handshake/14.0.0 which
the live mainnet bootnodes reject:
  protocols not supported: [/swarm/handshake/14.0.0/handshake]

2.7.1 was the last release before the bump. Node stays isolated on 2.8
no matter how many peers it dials, so PSS routing never works.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

hostinger/prod-stack.yaml

@@ -192,7 +192,10 @@ services:
 
 
   bee:
-    image: ethersphere/bee:latest
+    # Pinned to 2.7.1: Bee 2.8 ships handshake protocol v14 which the live
+    # mainnet bootnodes don't negotiate yet — node ends up isolated. Revisit
+    # when the network upgrades.
+    image: ethersphere/bee:2.7.1
     # NOTE: BEE_BLOCKCHAIN_RPC_ENDPOINT is silently ignored by Bee 2.8 — pass
     # the flag explicitly. Without it Bee logs "chain backend disabled" and
     # exits with "factory fail: chain disabled".