Function merge_match_modes 

pub fn merge_match_modes(prev: Option<MatchMode>, next: MatchMode) -> MatchMode

Worst-case match honesty rollup: fuzzy > anchored > exact (#1673 / #1674).

Shared by multi-op content edits, plan/tx aggregates, and replace_op path re-visits so every surface reports the same confidence ordering.

Public for embedder hosts that combine multiple MatchMode values from multi-op content edits (#1844).