Two geometry batching wins to cut draw calls:
1. portals.js — Convert N individual portal Mesh objects to a single
InstancedMesh. Online/offline brightness is encoded into per-instance
color (AdditiveBlending: output = bg + color), so one shared material
handles all portals. Exports refreshPortalInstanceColors() for health
checks to call after status updates.
2. platform.js — Replace 69 individual LineSegments (one per glass tile,
each with a cloned material) with a single merged LineSegments whose
BufferGeometry holds all tile edge vertices pre-transformed to world
position. glassEdgeMaterials export is kept as an empty array for
API compatibility.
3. weather.js — Update runPortalHealthChecks() to call
refreshPortalInstanceColors() instead of iterating portal group
children to update per-mesh material opacity.
Draw call reduction: ~72 → ~2 for these elements (69 edge + 3 portals).
Refs #415
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
