0.74.0

## More reliable iOS runs
Arbigent now warms up the iOS simulator when connecting to it. A freshly booted simulator can crash the XCTest runner on the first interaction ("App crashed or stopped while executing flow"), which was a common source of flaky iOS runs.
Arbigent waits for the device to become responsive and settle before the first scenario, so cold-start crashes are avoided — no extra setup needed on your side.

## Masked secrets in CLI help
Sensitive option values (such as API keys) are now masked in the CLI `--help` output, so they won't leak when you share your help text or logs.

## What's Changed
* Mask sensitive option values in CLI help output by @takahirom in https://github.com/takahirom/arbigent/pull/380
* Switch CLI E2E model to gemma-4-31b-it by @takahirom in https://github.com/takahirom/arbigent/pull/381
* Recover iOS device crashes by reconnecting and retrying by @takahirom in https://github.com/takahirom/arbigent/pull/382
* Revert iOS reconnect-retry; warm up the simulator instead by @takahirom in https://github.com/takahirom/arbigent/pull/383
* Warm up iOS simulator on connect to avoid cold-start runner crashes by @takahirom in https://github.com/takahirom/arbigent/pull/384


**Full Changelog**: https://github.com/takahirom/arbigent/compare/0.73.0...0.74.0