feat(universe): major moons stay named across the Solar System

[alowpoly]

Change

From high over the Solar System, the moons disappeared completely: once a planet's moon orbits shrink below a readable size, every moon's circle and name faded out. Now each planet's major moons (Io, Europa, Ganymede, Callisto, Titan, Rhea, Titania, Triton and the rest of the sourced groups in site/source/major-moons.json) follow the rule Earth already uses beside the Sun. A moon keeps its circle while that circle clears its planet's circle, and keeps only its name once its orbit collapses into the planet's circle. Names still compete for the shared label budget and collision space, so a crowded planet names fewer moons.

The planner receives the list as annotationLandmarks, next to the existing annotation priorities, through the universe runtime, the main-thread planner and the worker.

Evidence and limits

Proves the change: a desktop capture at 1440×900 of /sun/?overview=system (134 AU) on the local build. Io, Titan, Rhea, Titania, Umbriel and Triton are named beside their planets with no circles. Before the change, the same view named no moons. Europa, Ganymede, Callisto and Oberon lost the collision contest there to their planet, the Sun and neighbouring labels.

Checks: vitest on universe/world-context-planner, universe/prepared-world-context, universe/world-context-planner-client and labels (176 passed); tsc -p site.

Not checked: the phone view (12-label budget) and intermediate zooms where a moon's circle clears its planet's circle.