fix(docker): add extra delay after graph sync for reliable payments

Add 10-second delay after route verification succeeds to ensure
the graph is fully propagated before attempting funding payments.
Also increase max route check attempts from 12 to 15.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docker/dev.sh

@@ -281,10 +281,12 @@ ensure_lnd4_channel() {
 
             # Verify graph has propagated by checking if lnd-3 can route to lnd-4
             local route_attempts=0
-            while [[ $route_attempts -lt 12 ]]; do
+            while [[ $route_attempts -lt 15 ]]; do
                 local route=$(docker exec lnbits-lnd-3-1 lncli --network=regtest --rpcserver=lnd-3:10009 \
                     queryroutes --dest "$lnd4_pubkey" --amt 10000 2>&1)
                 if echo "$route" | grep -q '"total_amt"'; then
+                    # Route found - wait a bit more for full sync before payments
+                    sleep 10
                     break
                 fi
                 sleep 5