Default `render_scale=0.5` + TAA + no sharpening makes output blurry

[ElYaiko]

The engine ships with defaults that produce noticeably soft/blurry rendering on first run:

Setting	Default	Effect
render_scale	0.5	G-buffer, HDR, and composed RTs rendered at half resolution, then upscaled back to display size
taa_enabled	true	Temporal AA blends frames (current frame contributes only ~6% after first 4 frames), softening detail further
cas_strength	0.0	No sharpening applied — neither to the TAA-blended output nor the upscaled half-res

Without explicitly calling setRenderScale(1.0) and setTaaEnabled(false), the image is noticeably blurry even for simple scenes (test3d's single cube + grid, pong, etc.). On a 800×600 window this renders at 400×300 internally.

Location: native/shared/src/renderer/mod.rs lines 5965–5966, 6116.

Suggestions:

1. Default render_scale to 1.0 (native resolution) and let users opt into half-res for performance, or
2. Enable cas_strength by a non-zero value (e.g. 0.3) when render_scale < 1.0 so the upscaled output has some sharpening, or
3. At minimum document these defaults prominently (README, API docs, or a "quality presets" hint)

Related: the quality presets (QualityPreset.Medium etc.) don't touch render_scale or cas_strength, so even switching to Ultra leaves the image soft.