lightwalletd: adaptive reorg-lag tip + non-blocking startup coinsupply

Adaptive-lag: advertise a tip that trails the real tip by a reorg-rate-driven
lag (GetLatestBlock/GetLightdInfo) so wallets anchor shielded spends at a
settled height during reorg churn. Configurable via
-adaptive-lag/-lag-min/-lag-max/-lag-window; monitor_lwd.sh runs
-lag-min 4 -lag-max 12 -lag-window 30.

Startup coinsupply: the informational startup coinsupply RPC (result used only
for a log line) blocked the gRPC bind for minutes on a node whose supply index
is cold, keeping the lite endpoint down on every restart while it also starved
the block-cache ingestor. Run it in a goroutine so the bind is never blocked;
clients still get coinsupply on demand via the GetCoinsupply RPC.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

monitor_lwd.sh

@@ -10,7 +10,7 @@ set -euo pipefail
 
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
 LWD_BIN="$SCRIPT_DIR/lightwalletd"
-LWD_ARGS="-bind-addr lite.dragonx.is:9069 -conf-file $HOME/.hush/DRAGONX/DRAGONX.conf -no-tls"
+LWD_ARGS="-bind-addr lite.dragonx.is:9069 -conf-file $HOME/.hush/DRAGONX/DRAGONX.conf -no-tls -lag-min 4 -lag-max 12 -lag-window 30"
 LOGFILE="$SCRIPT_DIR/lwd-monitor.log"
 PIDFILE="/tmp/lwd-monitor.pid"
 RESTART_DELAY=5        # seconds to wait before restarting after a crash