Assign one project/category to many employees over a date range in one
action. Modal mirrors single-create + employee checklist + "include
weekends" toggle. Stores range entries grouped by contiguous eligible
days per employee (weekends-off → per-work-week chunks); per-day cap
skips days already at 3. POST /plan/entries/bulk + bulkCreateEntries
(reuses createEntry); summary audit + result counts. No migration.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
