Introduce VegaSidePanel, a right-hand command panel with three modes:
star (system summary), fleet (ship count selectors), and order
(distance, ETA, Accept/Cancel). Replaces the inline fleet-order flow
with a callback-driven architecture where the scene owns selection
state and the panel only reads the engine and reports clicks.
Add fleet detachment logic to VegaLogic:
- splitFleet: carve a new idle fleet from an existing one
- sendDetachment: validate against actual stacks, normalize duplicates,
probe reachability on a copy, and rollback on refusal
- etaTo: compute ETA scoped to the selected detachment (slowest hull
in the selection, not the whole fleet)
VegaStarMap gains blockPointer (prevent pan/zoom over the panel),
onEmptyClick (dismiss panel by clicking void), and a rotating selection
reticle.
Section 4b adds ~32 verification checks covering ETA accuracy, ship
conservation, out-of-range refusals, duplicate normalization, star-base
immobility, and the idle-fleet merge rule.
Updates mastervega-build-plan.md to document the new panel and
verification section.