sync-status: add cosmos/CometBFT handler (gaiad + cosmos batch)

Cosmos-hub has NO EVM RPC — eth_blockNumber checks don't apply. Add a --cosmos
handler that probes the CometBFT /status method: sync_info.catching_up=false =>
online, else syncing; optional head-gap check vs the drpc reference. sync-status.sh
dispatches protocol=cosmos -> check-health.sh --cosmos. eth/starknet/aztec untouched.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

sync-status.sh

@@ -54,7 +54,7 @@ for path in $pathlist; do
         fi
 
         case "$protocol" in
-            eth|starknet|aztec)
+            eth|starknet|aztec|cosmos)
                 ;;
             *)
                 # Protocol family known from the registry but no probe support
@@ -67,8 +67,10 @@ for path in $pathlist; do
 
         is_starknet=false
         is_aztec=false
+        is_cosmos=false
         [ "$protocol" = "starknet" ] && is_starknet=true
         [ "$protocol" = "aztec" ] && is_aztec=true
+        [ "$protocol" = "cosmos" ] && is_cosmos=true
 
         ref=''
         if [ -n "$2" ]; then
@@ -127,6 +129,12 @@ for path in $pathlist; do
                     echo "error"
                     exit 1
                 fi
+            elif $is_cosmos; then
+                # Cosmos/CometBFT: no chainid. Reference by drpc slug (optional — the node's
+                # own sync_info.catching_up is authoritative; ref only adds a head-gap check).
+                if [ -n "$chain_slug" ]; then
+                    ref=$($BASEPATH/reference-rpc-endpoint.sh --chain "$chain_slug" 2>/dev/null) || ref=""
+                fi
             else
                 # Ethereum chain ID detection
                 chain_id_response=$(curl -L --ipv4 -m 1 -s -X POST -H "Content-Type: application/json" --data '{"jsonrpc":"2.0","method":"eth_chainId","params":[],"id":1}' $RPC_URL)
@@ -155,6 +163,8 @@ for path in $pathlist; do
             $BASEPATH/check-health.sh "$RPC_URL" --aztec $ref
         elif $is_starknet; then
             $BASEPATH/check-health.sh "$RPC_URL" --starknet $ref
+        elif $is_cosmos; then
+            $BASEPATH/check-health.sh "$RPC_URL" --cosmos $ref
         else
             $BASEPATH/check-health.sh "$RPC_URL" $ref
         fi