Add shared ViewHistory<V> utility class that provides a proper navigation
stack for rApps with hierarchical views. Replaces hardcoded data-back
targets with stack-based back navigation across 10 rApps: rtrips, rmaps,
rtasks, rforum, rphotos, rvote, rnotes, rinbox, rschedule, rcart.
Rename rWork module to rTasks — directory, component (folk-tasks-board),
CSS, exports, domains, and all cross-module references updated.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
