add dynamic gasfee pricing as a signing client option - Feemarket/Osmosis

[ertemann]

Summary

Adds automatic gas price discovery for chains with dynamic feemarket modules (Osmosis EIP-1559 and Skip feemarket). Instead of manually setting static gas prices, CosmJS can now query current prices from the chain, preventing transaction failures from outdated pricing.

Changes

• New feemarket.ts: Query dynamic gas prices from Osmosis EIP-1559 and Skip feemarket modules
• Updated clients: SigningStargateClient and SigningCosmWasmClient now support DynamicGasPriceConfig
• Refactoring: Extracted calculateFeeForTransaction() helper
• Tests: Some unit tests and an end-to-end validation on Osmosis and Neutron testnets

Usage

const client = await SigningStargateClient.connectWithSigner(rpc, signer, {
  gasPrice: {
    denom: "uosmo",
    multiplier: 1.3,
    minGasPrice: GasPrice.fromString("0.0025uosmo"),
    maxGasPrice: GasPrice.fromString("0.1uosmo"),
  }
});

// Gas price queried automatically per transaction
await client.signAndBroadcast(address, messages, "auto");

Features

Graceful fallback to minGasPrice if feemarket query fails
Min/max constraint enforcement with configurable multiplier
backward compatible - existing code unchanged
Automatic chain detection for Osmosis variants

Inspired by Hermes relayer PR #4004.

[ertemann]

If there is a cleaner way to do this please advise

[ertemann]

throwaway mnemonic for you to test with.

[ertemann]

Just a complete integration test to validate the PR, can be removed once merged

[ertemann]

or should this actually go into cosmjs/types? they refer to /feemarket module ofcourse and not base SDK