v0.1.4

feat(cli): drop empty columns/tables automatically; keep ones with data

Schema sync now applies drops when they lose nothing — an empty table or a
column whose every value is NULL are removed automatically, while any table with
rows or column with data is refused and surfaced for review. Verified end-to-end:
an all-NULL column and an empty table were dropped; a column with data and a
table with a row were kept untouched.

- diff: destructive is now structured (Drop[]) so the caller can data-check each
- cli: syncSchema drops only when dropLosesNoData(); else lists for review
- cli: fix the `pulse new` next-steps hint (single `pnpm dev`, no stale gen/engine)

All packages bumped to 0.1.4.