Add renderer trace scope contract

docs/modernization/roadmap.md

@@ -421,7 +421,7 @@ texture mip-level validation, texture-upload/readback command validation,
 mipmap-generation command validation, frame-capture byte-size helpers,
 frame-capture command validation, render-target blit validation, texture-slot
 binding validation, blend-state validation, scissor-state validation,
-depth-state validation, trace interface validation, sampler-state validation,
+depth-state validation, trace marker/scope validation, sampler-state validation,
 and the canonical PanoPainter shader catalog now consumed by the legacy OpenGL
 app initialization path.
 `pp_renderer_gl` now exists as the first OpenGL backend library and owns pure
@@ -725,7 +725,8 @@ Results:
   PanoPainter shader catalog validation, explicit texture usage validation,
   texture mip-level validation, readback byte-size and command-order
   validation, texture-upload byte-count validation, mipmap-generation command
-  validation, frame-capture byte-size and command-order validation,
+  validation, trace marker/scope validation, frame-capture byte-size and
+  command-order validation,
   render-target blit validation, texture-slot binding validation, blend-state
   validation, scissor-state validation, render-pass color/depth/stencil clear
   validation, shader-uniform write validation, draw descriptor/range
@@ -834,7 +835,7 @@ Results:
   mipmap-generation/readback/frame-capture/blit validation plus explicit draw
   descriptor and texture-copy validation; it creates validated textures,
   render targets, shaders, meshes, and readback buffers, then records commands,
-  trace markers, render-pass
+  trace markers/scopes, render-pass
   color/depth/stencil clear intent, scissor state, depth state, blend state,
   shader uniform writes, texture/sampler binds, draw mesh inputs, explicit draw
   ranges, texture uploads/mipmap generations/copies/readbacks, frame captures,
@@ -842,7 +843,7 @@ Results:
   does not require a window or GL context.
 - `pano_cli record-render` exercises that headless recording renderer and emits
   JSON command counts, resource creation counts, target dimensions, backend
-  name, trace/draw summary, render-pass/depth-clear counts, and draw
+  name, trace marker/scope and draw summary, render-pass/depth-clear counts, and draw
   descriptor vertex/index totals, scissor/depth/blend-state plus
   shader-uniform/texture/sampler-bind/upload/texture-copy/readback/
   frame-capture/blit command/byte totals for agent automation, with an