feat(merge): diff Merge opens the 3-pane editor + conflict overview ruler

- The Merge button in the Diff window now hands a conflicting merge to the in-app
  3-pane editor (MergeModal routes 'conflict' through RequestConflictResolution,
  the same seam Approve uses) instead of dead-ending on a conflict message.
- Add a conflict overview ruler right of the Result pane: a proportional map of
  every conflict in the file, recolored by resolved state, click a tick to jump —
  so conflicts are findable in long files without scrolling.
- New MergeResolvedEdgeBrush token + conflictMap en/de key. Ui 128 + Loc 16 green.

src/ClaudeDo.Ui/CLAUDE.md

@@ -41,7 +41,7 @@ Design/     — Tokens.axaml (design tokens; merged before styles) + IslandStyle
 - **NotesEditorViewModel** — day navigator + bullet CRUD for daily notes via `INotesApi`.
 - **Modal VMs** — `SettingsModalViewModel` (four tabs: General, Worktrees, Files prompt-paths, Prime Claude incl. `DailyPrepMaxTasks` + prime-schedule rows), `ListSettingsModalViewModel` (name, working dir, commit type, per-list Model/SystemPrompt/AgentPath/MaxTurns with inherited-badge + reset, delete list), `RepoImportModalViewModel` (bulk-create lists from git repos found under chosen parents; already-wired repos disabled), `WeeklyReportModalViewModel` (range pickers default "since last standup weekday → today", cached per range, markdown via MarkdownView), `MergeModalViewModel` (single-task merge form, called from the diff modal), `WorktreesOverviewModalViewModel` (global/per-list worktree rows, batch merge + state ops), `UnfinishedPlanningModalViewModel` (Resume/FinalizeNow/Discard for a draft planning session), `WorkerConnectionModalViewModel` (offline help), `AboutModalViewModel`.
 - **Diff stack** — `UnifiedDiffParser` (static; parses `git diff` output into `DiffFileViewModel`s, detecting added/deleted/renamed/binary files and per-line numbers; `Flatten` injects file-header rows for a combined single-pane view). `DiffModalViewModel` has two modes: live worktree (branch diff vs base, with a Merge action) and commit-range `base..head` (`FromCommitRange = true` — shows a merged task's diff after its worktree is gone; no merge action). The view renders a file list with binary/empty placeholders via `DiffLinesView`.
-- **Planning/Conflicts** — `PlanningDiffViewModel` (per-subtask diffs via `GetPlanningAggregateAsync`, toggle to combined integration-branch diff, conflict warnings), `ConflictResolverViewModel` (in-app **Rider-style 3-pane merge editor** for both single-task and planning unit-merge conflicts: single-task starts the conflict merge, parses each conflicted file into stable/conflict `MergeFileSegment`s via the worker's `GetMergeConflictDocuments`; exposes the active file's three reconstructed documents — `ActiveOursText` / `ActiveResultText` / `ActiveTheirsText` (from `MergeFile.OursText/ResultText/TheirsText`; Result seeds unresolved conflicts with Ours) — plus `ActiveFile`/`SelectFileCommand` (multi-file switcher), `Current`/`Next`/`Previous` (focused-conflict nav), a per-active-file `PositionText` readout, per-block `AcceptOurs/Theirs/Both/Base` + `MergeFile.Compose`, and `CanContinue` gated on every file resolved + no binary; writes each file via `WriteConflictResolution`, continue/abort; **planning mode** via `OpenForPlanningAsync(parentId, subtaskId)` loads the current subtask's mid-merge conflicts without re-starting the merge and routes continue/abort to `ContinuePlanningMerge`/`AbortPlanningMerge`, so a unit-merge conflict re-opens the editor per subtask via the `PlanningMergeConflict` broadcast). The view (`Views/Conflicts/ConflictResolverView`) shows the whole file in three **AvaloniaEdit** panes — MAIN/ours (read-only) | editable Result | INCOMING/theirs (read-only) — with TextMate highlighting by extension (theme `StyleInclude` in `App.axaml`); a code-behind `IBackgroundRenderer` tints each conflict block (unresolved/resolved) across panes, an `IReadOnlySectionProvider` + `TextAnchor` regions keep only conflict spans editable in Result (edits flow back to the block); each unresolved conflict starts EMPTY (a thin marker bar); the between-pane gutter controls **toggle** each side in/out of the result — `›`/`‹` add MAIN/INCOMING in click order (first pick on top), clicking again removes that side — so a conflict can take main, incoming, both, or neither; a `FilesSummary` readout shows how many files still have conflicts, and the three panes share a proportional synced vertical scroll. Conflict block tints live in `Tokens.axaml` (`Merge*TintBrush`).
+- **Planning/Conflicts** — `PlanningDiffViewModel` (per-subtask diffs via `GetPlanningAggregateAsync`, toggle to combined integration-branch diff, conflict warnings), `ConflictResolverViewModel` (in-app **Rider-style 3-pane merge editor** for both single-task and planning unit-merge conflicts: single-task starts the conflict merge, parses each conflicted file into stable/conflict `MergeFileSegment`s via the worker's `GetMergeConflictDocuments`; exposes the active file's three reconstructed documents — `ActiveOursText` / `ActiveResultText` / `ActiveTheirsText` (from `MergeFile.OursText/ResultText/TheirsText`; Result seeds unresolved conflicts with Ours) — plus `ActiveFile`/`SelectFileCommand` (multi-file switcher), `Current`/`Next`/`Previous` (focused-conflict nav), a per-active-file `PositionText` readout, per-block `AcceptOurs/Theirs/Both/Base` + `MergeFile.Compose`, and `CanContinue` gated on every file resolved + no binary; writes each file via `WriteConflictResolution`, continue/abort; **planning mode** via `OpenForPlanningAsync(parentId, subtaskId)` loads the current subtask's mid-merge conflicts without re-starting the merge and routes continue/abort to `ContinuePlanningMerge`/`AbortPlanningMerge`, so a unit-merge conflict re-opens the editor per subtask via the `PlanningMergeConflict` broadcast). The view (`Views/Conflicts/ConflictResolverView`) shows the whole file in three **AvaloniaEdit** panes — MAIN/ours (read-only) | editable Result | INCOMING/theirs (read-only) — with TextMate highlighting by extension (theme `StyleInclude` in `App.axaml`); a code-behind `IBackgroundRenderer` tints each conflict block (unresolved/resolved) across panes, an `IReadOnlySectionProvider` + `TextAnchor` regions keep only conflict spans editable in Result (edits flow back to the block); each unresolved conflict starts EMPTY (a thin marker bar); the between-pane gutter controls **toggle** each side in/out of the result — `›`/`‹` add MAIN/INCOMING in click order (first pick on top), clicking again removes that side — so a conflict can take main, incoming, both, or neither; a `FilesSummary` readout shows how many files still have conflicts, and the three panes share a proportional synced vertical scroll. A conflict overview ruler right of the Result pane (`ConflictMap`) maps every conflict in the file proportionally (click a tick to jump) — handy for long files. Conflict block tints live in `Tokens.axaml` (`Merge*TintBrush`). The editor is reached from review **Approve** on conflict and from the **Merge** button in the Diff window (a conflicting `MergeTask` hands off to the resolver via `RequestConflictResolution`).
 
 ## Services