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.

docs/architecture.md

@@ -78,6 +78,8 @@ Comparison views reserve no separate metadata header or native-buffer help foote
 
 Each comparison owns its split/unified mode and split axis; startup defaults apply only when opening a comparison. Source alignment and file-side availability stay independent of presentation. Unified display rows carry a side projection: equal context maps both sources, changed runs emit Before rows followed by After rows, and folds retain aligned coordinates. Native navigation/editing continues to bind source buffers rather than a synthetic unified document. The TUI reuses side-specific syntax/wrap/overlay pipelines in one unified region or the existing axis-based split geometry, exposing only the active logical side for unified hit-testing and directional focus.
 
+The resolver owns a dedicated native tab with immutable input buffers and shared editable Result buffers, independent of historical comparison state. `resolve` reads all alternating jj merge-tree terms from immutable Git-backed `jj:trees` metadata; marker parsing only provides region navigation and draft replacement. Session background jobs load inputs and perform guarded saves. The write path holds jj's working-copy lock while validating checkout identity and on-disk data and installing the chosen result, then delegates snapshot/status authority to jj. Save aliases and shared Result tabs route through the same guards. TUI resolver geometry reuses native document rendering, with two inputs above Result or a single selected input at narrow widths.
+
 `Editor::scroll_distance()` supplies the session-wide optional edge margin. The TUI applies it to document/diff visual rows and unwrapped text columns, and retains independent picker offsets across navigation frames. Picker windows exclude their fixed chrome and align whole multi-row entries. File projections carry a monotonic viewport revision, so catalog/filter/expansion changes invalidate picker identity without hashing the entire catalog on every redraw. Metadata-only status changes do not move the viewport. Explicit LSP/wrap-toggle anchors and detached wheel views retain precedence.
 
 Mouse wheel input uses the last rendered document/panel rectangles for hit-testing. Document offsets and explorer scroll state remain frontend-owned; three-row wheel steps never become document cursor motions. Manual document views persist until logical caret-reveal, caret/selection, mode, revision, or buffer changes; offscreen primary and browsing-selection cursors are not placed. Hover wheel input reuses the existing editor-owned popup scrolling.