GitLab

Previously, preCheckMixedChannelRisk() skipped when selectedPlatforms
had more than one entry, and the catch block in submitBulkUpdate had no
409 handling — so multi-platform conflicts just showed a generic error.

- Rename canPreCheck(): only call pre-check API for single-platform
  antigravity/anthropic selections (API requires a single platform param)
- Pass `built` into preCheckMixedChannelRisk() so pendingUpdatesForConfirm
  is set before returning false
- submitBulkUpdate: add 409 mixed_channel_warning catch as fallback for
  multi-platform case, saving baseUpdates for retry
- Remove needsMixedChannelCheck() gate on confirm_mixed_channel_risk flag;
  use mixedChannelConfirmed alone so multi-platform retry also works