v5.1.2 - Now titles no longer silently truncated

Fixed

• Now item titles are no longer silently truncated. A title longer than
  the 200-character limit was quietly cut to fit, discarding everything past
  the cutoff. Since Now items have no body field, that text was lost with no
  warning. Over-long titles are now rejected with a clear error that reports
  the actual length and suggests linking a note for long detail. The
  200-character single-line limit itself is unchanged.

Internal

• Removed the dead setup_schema() / setup_fts() methods from the database
  backend (PostgreSQL implementation + abstract declarations). They were never
  called; schema creation runs exclusively through the migrator
  (run_migrations). No behaviour change.