The globe draws the poles as they are, and nothing while idle

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The globe is a UV sphere: towards the poles its triangles narrow to
slivers, and texture coordinates interpolated across them pinched the
map into a star around each pole. Each pixel now computes its own
coordinates from its exact point on the sphere, with seam-safe mipmap
gradients; the map wraps horizontally and gets 8x anisotropic
filtering.

That showed a flaw in the day texture: NASA's mosaic has a lighter
strip at its east edge near the poles, a line from each pole once drawn
exactly. The day texture is now built from NASA's original Blue Marble
(December 2004) by tools/globe/prepare-day-texture.py, which blends
that strip into the map where both sides of the seam agree; same
4096x2048 size, provenance and hashes in SOURCES.md.

globe.gl redrew 60 times a second even when nothing moved; it now draws
only during camera flights, hover pulses, auto-rotation and the
reader's drags, so an idle globe costs no GPU time.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LsXgEaXee4GCU1hwYgPJXw

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