Replace the Base|Ours|Theirs read-only columns + single-conflict result with a
whole-file 3-pane editor: Ours (read-only) | editable Result | Theirs (read-only),
reconstructed from the active file's segments so the panes line up on stable text.
- IBackgroundRenderer paints each conflict block (unresolved=blood, resolved=green)
across all three panes.
- Result document edits are gated by an IReadOnlySectionProvider (stable text is
read-only; only conflict regions, tracked via TextAnchors, are editable); edits
flow back to the owning block.
- Between-pane gutters host inline accept controls (>/< ) positioned per conflict;
click accepts ours/theirs into the result.
- Proportional synced vertical scroll across the panes; file switcher + change-nav
arrows (F8 / Shift+F8); active-file 'M conflicts - K resolved' readout.
- Merge block tints + AmberBrush tokens; en/de keys for the new labels.
Seam unchanged. App builds; Ui.Tests 128, Localization.Tests 16.
c4d1acc75b