tac: add tacchaind pruned compose for mainnet and spb

Source-build Dockerfile (tacchain v1.6.0), init script with statesync via
cometbft-common.sh, EVM RPC/WS on 8545/8546, and dshackle slugs tac/tac-spb.

compose_registry.json

@@ -8463,6 +8463,36 @@
       "starknet-sepolia-pathfinder-pruned"
     ]
   },
+  {
+    "chain": "mainnet",
+    "client": "tacchaind",
+    "compose_file": "tac/tacchaind/tac-mainnet-tacchaind-pruned",
+    "features": [],
+    "network": "tac",
+    "node": "config",
+    "relay": null,
+    "stack": null,
+    "type": "pruned",
+    "volumes": [
+      "tac-mainnet-tacchaind-pruned",
+      "tac-mainnet-tacchaind-pruned_config"
+    ]
+  },
+  {
+    "chain": "spb",
+    "client": "tacchaind",
+    "compose_file": "tac/tacchaind/tac-spb-tacchaind-pruned",
+    "features": [],
+    "network": "tac",
+    "node": "config",
+    "relay": null,
+    "stack": null,
+    "type": "pruned",
+    "volumes": [
+      "tac-spb-tacchaind-pruned",
+      "tac-spb-tacchaind-pruned_config"
+    ]
+  },
   {
     "chain": "alethia",
     "client": "geth",