Reduce moving-background shimmer in Godot terminal games

[nicodes]

Moving Godot backgrounds shimmer on small terminal grids because the previous low-resolution render and bilinear reduction undersample fine detail. Default smooth sampling renders at up to twice the previous scale, capped at the authored viewport size, then uses Godot's mipmap-based trilinear reduction. The game keeps its camera, logical coordinates, physics and native text overlays. Honeyvale needs no source changes.

TERMCADE_GODOT_SAMPLING=fast retains the cheaper previous sampling; smooth or unset selects the new default. Fine detail is softer, and rendering costs more. No temporal blur, camera snapping or game-specific adjustments are introduced. Existing packages require re-exporting.

A real exported fixture pans a camera diagonally over high-frequency detail. After four settling frames, 24 measured frames show mean per-pixel brightness change falling from 82.12 to 2.16; the regression requires at least 75% reduction. Honeyvale's warmed diagonal replay at 96×28 quadrant cells measured 4.74 ms fast versus 6.68 ms smooth exchange; at 160×45 smooth exchange measured 11.75 ms plus 2.49 ms terminal composition. Measurements exclude startup and emulator paint.

Validation: full local Make shipping gates and refined camera-pan race test; owned Honeyvale PTY with readable Play/HUD/bag controls and clean exit; five-platform archives and actual exported engine/CLI tests. Canonical docs retain immutable measurements and source hashes.

This draft includes and supersedes the earlier unmerged Godot exporter/native-text draft #40. The experimental Linux native runtime requires trusted games, Godot 4.7.2, Xvfb and Mesa. No marketplace adoption, release, merge or deployment is included.

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