v0.3.0 — gas_estimated moves onto the plan

What changed

Breaking: gas_estimated has moved out of each transaction dict and onto the plan.

render_eoa used to write a gas_estimated bool into every transaction. eth_account validates
the dict it is handed and rejects any key it does not recognise, so the transactions a plan returned
could not be signed as returned:

acct.sign_transaction(plan["transactions"][0])
# TypeError: Unknown kwargs: ['gas_estimated']

The README worked around it in prose, telling you to pop the key first. That put a preparation step
in front of the first thing every EOA consumer does, and pointed the traceback at eth_account
rather than at this package.

"Did this limit come from a live estimate" is not a field an Ethereum transaction has. It is
provenance about the plan, so it now travels beside the transactions:

plan["transactions"][i]     # signs exactly as returned, no preparation
plan["gas_estimated"][i]    # same index, same answer

plan["gas_estimated"] is a list of one bool per transaction, and None in calls mode — nothing
was estimated there, so [] or [False, ...] would both assert something untrue.

Migrating

Read plan["gas_estimated"][i] instead of plan["transactions"][i]["gas_estimated"]. If you
followed the old README and pop the key, use the tolerant form — the strict tx.pop("gas_estimated")
now raises KeyError:

tx.pop("gas_estimated", None)   # or just delete the line

Consumers in tx_mode="calls" are unaffected: they read plan["calls"] and never rendered
transactions.

Also in this release

• Reverts are reported as sentences. A refused plan now says
  Transfer 1000000.0 USDC to 0x7a25... would revert: execution reverted: ERC20: transfer amount exceeds balance. Previously this was web3's exception repr, which for a custom error printed the
  same hex string twice and named neither the call nor the error. The six OpenZeppelin v5 ERC-20
  custom errors decode by name; an unregistered selector says so rather than guessing.
• tx_mode="calls" now simulates the first call with one eth_call, so "a plan certain to
  revert is never built" holds for smart accounts and not only for EOAs, which get it free from gas
  estimation. A sender with no code deployed yet is skipped, and estimate_gas=False turns
  simulation off in both modes. This catches what the preflight flag's balance and allowance reads
  cannot: blocklists, pauses and transfer hooks.
• ERC20_ERRORS_ABI is exported for consumers decoding reverts of their own.

Compatibility

The same plans.py is mirrored in langchain-erc8004 and langchain-uniswap-v2; both already
carry this change, so the plan shape is now identical across all three.