The preceding commits taught the import worker to coerce custom CSV
column values into JSON booleans and numbers via `coerceCustomValue`
in `apps/api/src/jobs/import-processor.ts`. Without a corresponding
docs update, users can't predict whether a cell like `01234` lands as
a string or as the number `1234`, or which segment-filter operators a
field will expose after import.
Add two bullets to the existing "Rules and limits" list in the
contact-import guide, adjacent to the **Date columns** bullet that
already documents value typing for ISO 8601 dates. The bullets mirror
that style and brevity: one names the boolean keyword set and the
toggle it unlocks in segment filters, the other names the numeric
pattern, the `gt`/`lt` operators it unlocks, and the deliberately
preserved-as-string forms (leading zeros, `+`-prefixed, scientific
notation) so users keep their IDs, zip codes, and phone numbers
intact.
No other content is touched. Closes the documentation gap for
useplunk/plunk#390.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
