Add renderer draw descriptor contract

docs/modernization/roadmap.md

@@ -725,10 +725,11 @@ Results:
   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, backend-neutral resource factory validation, recording
+  validation, draw descriptor/range validation, backend-neutral resource
+  factory validation, recording
   render-pass clear/scissor/depth/blend/shader-uniform/texture/sampler-bind/
   upload/readback/frame-capture/blit command capture, draw mesh-input capture,
-  and invalid catalog rejection.
+  explicit draw-range capture, and invalid catalog rejection.
 - `pp_paint_renderer_compositor_tests` passed.
 - `pp_ui_core_color_tests` passed.
 - `pp_ui_core_layout_value_tests` passed.
@@ -825,18 +826,19 @@ Results:
   renderer-owned resource factory and
   command-order/render-pass-clear/scissor-state/depth-state/blend-state/
   texture-bind/sampler-bind/shader-uniform/texture-upload/readback/
-  frame-capture/blit validation; it creates validated textures, render targets,
-  shaders, meshes, and readback buffers, then records commands, trace markers,
-  render-pass color/depth/stencil clear intent, scissor state, depth state,
-  blend state, shader uniform writes, texture/sampler binds, draw mesh inputs,
+  frame-capture/blit validation plus explicit draw descriptor validation; it
+  creates validated textures, render targets, shaders, meshes, and readback
+  buffers, then records commands, trace markers, 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,
   uploads/readbacks, frame captures, and render-target blits, giving automation
   a backend-neutral render path that 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
-  vertex/index totals, scissor/depth/blend-state plus shader-uniform/texture/
-  sampler-bind/upload/readback/frame-capture/blit command/byte totals for
-  agent automation, with an expected-failure smoke for oversized
+  descriptor vertex/index totals, scissor/depth/blend-state plus
+  shader-uniform/texture/sampler-bind/upload/readback/frame-capture/blit
+  command/byte totals for agent automation, with an expected-failure smoke for oversized
   render/readback targets.
 - `pano_cli simulate-document-history` exercises pure document history
   apply/undo/redo behavior and emits JSON layer/frame/history state for agent