Move texture defaults behind renderer gl

docs/modernization/roadmap.md

@@ -459,6 +459,10 @@ active texture units to `pp_renderer_gl`.
 `NodeStrokePreview` brush preview rendering now delegates depth/scissor/blend
 state, viewport/clear-color queries, active texture units, 2D texture targets,
 copy targets, and sampler filters/wraps to `pp_renderer_gl`.
+Legacy `Texture2D`, `TextureManager`, `Sampler`, and `RTT` public headers no
+longer expose raw OpenGL enum defaults; default texture formats, sampler
+filters/wraps, and render-target formats are resolved through backend-owned
+overloads.
 The existing renderer classes are not yet fully
 behind the renderer interfaces.