Improve Dogecoin fee estimation to reduce overly high fees

The fee estimation was calculating ~/bin/bash.20 fees when it should be much lower.

Changes:
- Use 6 block target (~1 hour) instead of 2 blocks for cheaper estimates
- Reduce transaction size estimate from 0.5KB to 0.25KB (more realistic for DOGE)
- Lower fallback fee from 0.01 DOGE to 0.002 DOGE (~/bin/bash.0006 vs /bin/bash.003)
- Update development.ini default to match new lower fallback

This should reduce typical fee estimates from ~/bin/bash.20 to ~/bin/bash.02-0.05 range,
making Dogecoin payments more cost-effective for users while still covering
both inbound and sweep transaction costs.

development.ini

@@ -93,8 +93,8 @@ dogecoin.rpc_pass = ${MPS_DOGECOIN_RPC_PASS:-change_this_password_in_production}
 dogecoin.confirmations.petty = ${MPS_DOGECOIN_CONFIRMATIONS_PETTY:-2}
 dogecoin.confirmations.mid = ${MPS_DOGECOIN_CONFIRMATIONS_MID:-6}
 dogecoin.confirmations.high = ${MPS_DOGECOIN_CONFIRMATIONS_HIGH:-20}
-# Fee buffer for customer payments (in DOGE)
-dogecoin.fee_buffer = ${MPS_DOGECOIN_FEE_BUFFER:-0.01}
+# Fee buffer for customer payments (in DOGE) - reduced from 0.01 to 0.002 for more reasonable fees
+dogecoin.fee_buffer = ${MPS_DOGECOIN_FEE_BUFFER:-0.002}
 dogecoin.rate_source_url = ${MPS_DOGECOIN_RATE_SOURCE_URL:-https://api.coingecko.com/api/v3/simple/price?ids=dogecoin&vs_currencies=usd}
 
 # set this to the path of your private DKIM key.