Merge branch 'mm/diff-process-hunks' into seen

A new 'diff.<driver>.process' configuration has been introduced to allow a long-running external process to act as a hunk provider, enabling external tools to control which lines Git considers changed while leaving all output formatting (word diff, color, blame, etc.) to Git's standard pipeline. * mm/diff-process-hunks: diff: consult oid-only hunk providers via diff.<driver>.process userdiff: add diff.<driver>.process config sub-process: add a gentle status read sub-process: separate process lifecycle from hashmap management blame: read precomputed hunks diff: read precomputed hunks for stat output diff: record precomputed hunks during stat output diff-hunks: add the store format, library, and command diff: introduce a hunk provider interface gitattributes: document how external diff drivers relate to diff features