Replaces the word-based validation with character-based validation
as originally requested in #971. The 6-word limit was causing issues
with small words and separators being counted equally, and didn't
match the original requirement for a character limit.
Changes:
- Backend: Replace wordCount validator with len validator (1-150 chars)
- Frontend: Replace word count validation with character length check
- UI already has line-clamp-3 for display truncation
Fixes#998
b1a0a728d2