Route planning unit-merge conflicts through ConflictResolverViewModel
(OpenForPlanningAsync) and delete the old ConflictResolutionViewModel dialog.
Add active-file 3-pane reconstruction (MergeFile OursText/TheirsText/ResultText,
ActiveFile, SelectFileCommand, active-file readout) as the VM foundation for the
Rider-style editor. Seam preserved; Ui.Tests 128/128.
Kontext: Auf der Hub/Client-Ebene existieren zwei fast gleichnamige Methodenpaare mit unterschiedlicher Semantik: ContinueMerge/AbortMerge (Single-Task-Konflikt-Resolver, Layer C) vs. ContinuePlanningMerge/AbortPlanningMerge (Unit-Merge eines Parents mit Kindern). Verwechslungsgefahr.
Änderungen (NUR die Hub/Client/UI-Ebene umbenennen):
1. src/ClaudeDo.Worker/Hub/WorkerHub.cs: ContinueMerge → Con
ClaudeDo-Task: 5f2e0f88-d4c9-490b-95a7-46244465dbb6