.trimws_col: Trim whitespace from a single column in a data frame
Description
Strips leading and trailing whitespace from character or factor columns.
This prevents mismatches between moderator levels, mod.order values,
and model coefficient names (e.g., "Echinodermata " vs "Echinodermata").
Usage
.trimws_col(x)
Value
The same vector with whitespace trimmed (character/factor only).