Fixes:
- Move batch size, upsert strategy, include source reference
from Config tab to Target Config tab (Write Settings section)
- Fix 'Dataset #26' fallback — look up real datasource name
via API when source_table is not saved in job data
- Persist include_source_reference in save payload and
restore from job data on load (was a pre-existing gap)
QA review fixes:
- Update @BRIEF contracts for both tabs
- Fix import indentation in +page.svelte
Other: help tooltips on translate pages, flow hint on list page,
git migration manager components, dashboard hub pages,
migration settings pages