Fix: re-add Crab to blacklist, mistakenly dropped in earlier cleanup

Real user hit a stuck "Connecting..." state on the Crab chain on a
live build. Root cause: the ORIGINAL blacklist (before today's
cleanup) correctly listed this chain as "Darwinia Crab" with chain_id
86e49c...c3a - I dropped that entry during the 2026-07-08 blacklist ID
correction, having concluded it "no longer exists upstream" based on
a name search for "darwinia"/"crab" that didn't match because the
chain's actual name field is just "Crab", not "Darwinia Crab" - a
search-term miss, not evidence the chain or its chain_id had changed.
It's been in chains.json all along with the same id and the same dead
RPC (crab-rpc.darwinia.network, confirmed unreachable again live
2026-07-08).

Re-verified against live chains.json before re-adding - it's really
there, and the RPC is really dead.

chains/v16/chains_dev.json

@@ -7580,68 +7580,6 @@
       "ethereumBased"
     ]
   },
-  {
-    "chainId": "86e49c195aeae7c5c4a86ced251f1a28c67b3c35d8289c387ede1776cdd88b24",
-    "parentId": "b0a8d493285c2df73290dfb7e61f870f17b41801197a149ca93654499ea3dafe",
-    "name": "Crab",
-    "assets": [
-      {
-        "assetId": 0,
-        "symbol": "CRAB",
-        "precision": 18,
-        "priceId": "darwinia-network-native-token",
-        "icon": "https://raw.githubusercontent.com/novasamatech/nova-utils/master/icons/chains/white/Crab.svg"
-      },
-      {
-        "assetId": 1,
-        "symbol": "CKTON",
-        "precision": 18,
-        "type": "statemine",
-        "icon": "https://raw.githubusercontent.com/novasamatech/nova-utils/master/icons/tokens/white/CKTON.svg",
-        "typeExtras": {
-          "assetId": "1026"
-        }
-      }
-    ],
-    "nodes": [
-      {
-        "url": "wss://crab-rpc.darwinia.network/",
-        "name": "Darwinia node"
-      },
-      {
-        "url": "wss://darwiniacrab-rpc.dwellir.com",
-        "name": "Dwellir node"
-      },
-      {
-        "url": "wss://crab-rpc.darwiniacommunitydao.xyz",
-        "name": "Community node"
-      }
-    ],
-    "explorers": [
-      {
-        "name": "Subscan",
-        "extrinsic": "https://crab.subscan.io/extrinsic/{hash}",
-        "account": "https://crab.subscan.io/account/{address}"
-      }
-    ],
-    "externalApi": {
-      "history": [
-        {
-          "type": "subquery",
-          "url": "https://api.subquery.network/sq/nova-wallet/nova-wallet-darwinia"
-        }
-      ]
-    },
-    "types": {
-      "url": "https://raw.githubusercontent.com/novasamatech/nova-utils/master/chains/v2/types/darwinia_crab.json",
-      "overridesCommon": true
-    },
-    "icon": "https://raw.githubusercontent.com/novasamatech/nova-utils/master/icons/chains/gradient/Crab.svg",
-    "addressPrefix": 42,
-    "options": [
-      "ethereumBased"
-    ]
-  },
   {
     "chainId": "4a587bf17a404e3572747add7aab7bbe56e805a5479c6c436f07f36fcc8d3ae1",
     "parentId": "91b171bb158e2d3848fa23a9f1c25182fb8e20313b2c1eb49219da7a70ce90c3",