Add renderer texture copy command

docs/modernization/roadmap.md

@@ -726,10 +726,11 @@ Results:
   validation, blend-state validation, scissor-state validation,
   render-pass color/depth/stencil clear validation, shader-uniform write
   validation, draw descriptor/range validation, backend-neutral resource
-  factory validation, recording
+  factory validation, texture-copy validation, recording
   render-pass clear/scissor/depth/blend/shader-uniform/texture/sampler-bind/
-  upload/readback/frame-capture/blit command capture, draw mesh-input capture,
-  explicit draw-range capture, and invalid catalog rejection.
+  upload/texture-copy/readback/frame-capture/blit command capture, draw
+  mesh-input capture, 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.
@@ -826,20 +827,21 @@ 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 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.
+  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
+  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/copies/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
   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.
+  shader-uniform/texture/sampler-bind/upload/texture-copy/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
   automation.