Drag handles for sidebar / context / editor split were pure
pointer-Listeners — no Tab focus, no arrow-key adjust, no Semantics.
Each now wraps in a FocusableActionDetector with arrow shortcuts (10
px fine / 50 px coarse for the column handles, 2% / 10% for the
editor split) and a slider Semantics node that announces the current
size. The CLI verb half is split out as T-119 and waits on T-99.
Co-Authored-By: Claude <noreply@anthropic.com>
jpmschweitzerandClaude
5d1237501c