Add renderer frame capture contract

docs/modernization/build-inventory.md

@@ -285,12 +285,12 @@ Known local toolchain state:
   source code reintroduces raw `GL_*`/`WGL_*` constants outside the allowed
   legacy OpenGL implementation files.
 - `pp_renderer_api` exposes a headless `RecordingRenderDevice` that validates
-  command order, readback bounds, and destination buffer sizes, records render
-  and readback commands, and records trace markers without a window or GL
-  context.
+  command order, readback bounds, frame-capture sources, and destination buffer
+  sizes, records render/readback/frame-capture commands, and records trace
+  markers without a window or GL context.
 - `pano_cli record-render` exposes the recording renderer through JSON
-  automation, including readback command/byte totals, and is covered by
-  `pano_cli_record_render_smoke` plus
+  automation, including readback and frame-capture command/byte totals, and is
+  covered by `pano_cli_record_render_smoke` plus
   `pano_cli_record_render_rejects_oversized_target`.
 - `pano_cli simulate-document-history` exposes `pp_document::DocumentHistory`
   apply/undo/redo state through JSON automation and is covered by

docs/modernization/roadmap.md

@@ -416,7 +416,8 @@ adding new backends.
 Status: started. `pp_renderer_api` exists as a headless renderer-neutral target
 with texture descriptor, byte-size, viewport, mesh, readback bounds, command
 context, render device, shader program descriptor, mesh, render target,
-readback byte-size helpers, readback command validation, trace interface
+readback byte-size helpers, readback command validation, frame-capture
+byte-size helpers, frame-capture command validation, trace interface
 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
@@ -718,8 +719,8 @@ Results:
   plus malformed payload rejection at the export boundary.
 - `pp_renderer_api_tests` passed, including shader descriptor validation,
   PanoPainter shader catalog validation, readback byte-size and command-order
-  validation, recording readback command capture, and invalid catalog
-  rejection.
+  validation, frame-capture byte-size and command-order validation, recording
+  readback/frame-capture command capture, and invalid catalog rejection.
 - `pp_paint_renderer_compositor_tests` passed.
 - `pp_ui_core_color_tests` passed.
 - `pp_ui_core_layout_value_tests` passed.
@@ -813,13 +814,13 @@ Results:
   reintroduces raw `GL_*`/`WGL_*` constants outside the allowed legacy OpenGL
   implementation files.
 - `pp_renderer_api` now includes a headless `RecordingRenderDevice` with strict
-  command-order/readback validation and command/trace/readback capture, giving
-  automation a backend-neutral render path that does not require a window or GL
-  context.
+  command-order/readback/frame-capture validation; it records commands, trace
+  markers, texture readbacks, and frame captures, 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, target dimensions, backend name, trace/draw summary, and
-  readback command/byte totals for agent automation, with an expected-failure
-  smoke for oversized render/readback targets.
+  readback/frame-capture 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.