fix: propagate ABCI errors instead of swallowing them

[theforager]

Fixes #183

Issue

When simulation fails, abciQuery wasn't checking the ABCI response code. If fromBase64() happened to succeed on empty/garbage data, the error got swallowed entirely. Users end up seeing gasWanted: 0, gasUsed: 1000 with no idea why.

Fix

Check response['code'] !== 0 before trying to decode. If it's non-zero, throw an AbciError with the code and log message so callers can actually see what went wrong.

Added a new AbciError type to @interchainjs/types that includes the raw ABCI code and log:

try {
  await client.simulate(tx);
} catch (e) {
  if (e instanceof AbciError) {
    console.log(`code ${e.abciCode}: ${e.log}`);
  }
}

Changes

- packages/types/src/errors.ts - new AbciError class
- packages/utils/src/rpc.ts - check response code, use typed errors
- packages/utils/src/rpc.spec.ts - tests for error handling

Backward compatible since AbciError still extends Error.