refactor(diff): render planning mode per file and retire DiffLinesView

src/ClaudeDo.Ui/CLAUDE.md

@@ -31,7 +31,7 @@ ViewModels/
   Conflicts/  — ConflictResolverViewModel + ConflictModels
 Views/          — mirrors the VM layout; Islands/Detail/ holds TaskHeaderBar,
                   DescriptionStepsCard, WorkConsole; plus SessionTerminalView
-Views/Controls/ — MarkdownView, ModalShell, ThemedDatePicker, DiffLinesView, InheritedBadge,
+Views/Controls/ — MarkdownView, ModalShell, ThemedDatePicker, DiffTextView, InheritedBadge,
                   AgentConfigEditor
 Design/         — Tokens.axaml (design tokens; merged before styles)
                   + IslandStyles.axaml (component styles + the filled icon geometry library)
@@ -68,7 +68,10 @@ warn/error filter), `WorkerConnectionModalViewModel`, `AboutModalViewModel`.
 ## Diff & Conflicts
 
 `UnifiedDiffParser` (static) + `DiffModels.cs` shared types + `DiffViewerViewModel` (one unified
-read-only viewer, Files and Planning modes) + `DiffLinesView`.
+read-only viewer, Files and Planning modes) render through `DiffAlignment` (pure — pairs diff
+lines into side-by-side rows and computes word-diff spans) and `DiffTextView` (AvaloniaEdit +
+TextMate highlighting, unified/split layout, optional line wrap, synced scrolling). The
+split/wrap toggles persist to `ui.config.json` via `AppSettings`.
 `ConflictResolverViewModel` is an in-app Rider-style 3-pane AvaloniaEdit merge editor for both
 single-task and planning unit-merge conflicts. Full detail →
 [review-merge](../../docs/explore-notes/review-merge.md).