feat: resolve current jj working-copy conflicts

Add a dedicated native resolver workspace with all side/base inputs,
shared editable Results, region choices, retained per-file status,
responsive rendering, and explicit nontext file choices.

Guard writes with jj working-copy locking, frozen checkout identity,
exact disk baselines, native dirty-buffer protection, and asynchronous
jj snapshot/status confirmation. Historical comparisons remain readonly.

Verified all 916 tests and live isolated terminal workflows covering text
regions, narrow layouts, binary bytes and symlink targets/types.
Clippy completes with pre-existing warnings only.

Size exception: 2614 implementation additions/deletions excluding tests
and docs. Native workspace integration, explicit file choices and the
safe save/check operation are retained as one complete behavioral slice.

README.md

@@ -40,6 +40,7 @@ Vamp starts in Normal mode. Press `i`, type text, then Esc to return to Normal.
 | Floating/docked explorer in Normal or Visual | Space then `o` / Space then `e` |
 | Repository diff in Normal | `:diff`; choose Before then After, Tab changes category, type to search; Esc closes the selector; Working or checkout-matched pinned After is editable; `:diff.close` exits the comparison |
 | Diff layout in Normal | Space then `v` cycles split/unified; Space then `s` flips left/right vs above/below split |
+| Resolve jj working-copy conflicts | `:resolve`; inspect readonly inputs, edit Result or `:resolve.use_source N`, then `:w` to save and confirm with jj |
 
 Space is the default leader: press its suffix keys in order, not simultaneously. The [editing guide](docs/editing.md) contains the complete key table and behavior reference.