Create a sprite asset from a texture's context menu

The sprite takes the whole image at its pixel size and the texture's name,
numbered like any other clash. CreateAssetCommand now accepts starting
properties; they go through the schema in execute, so an unknown key or a
bad value is refused before the project is touched, and one undo removes
the asset.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

README.md

@@ -447,6 +447,11 @@ sizes up to 200 × 200, 3135 do not survive the round trip through a division, a
 would leave the button standing after its own click. The pixel size is compared exactly, because
 those two numbers are written as they are.
 
+**A sprite straight from a texture.** Right-click a texture in the asset list → *Create sprite
+from texture* makes a sprite asset that wears the whole picture at its pixel size, named after the
+texture and selected. It is the same as creating a sprite, picking the texture and clicking *Set to
+W × H px*, but in one undo step.
+
 Rendering a frame is a texture matrix on the fill, not a Pixi sub-texture — a Graphics fill
 ignores a `Texture`'s `frame` (measured, see `viewport/textureFill.ts`). One consequence is
 worth having: a sheet stays **one** GPU upload however many frames of it are on screen.
@@ -619,7 +624,7 @@ npm run check        # typecheck + lint + format:check + tests, what CI would ru
                      #   code is lost (tail's is reported), so a red run reads as green
 npm run build        # writes dist/ and regenerates index.html
 export GM_REMOTE=user@host                                    # optional: run the browser elsewhere; see below
-node tools/seed-e2e.mjs && node tools/e2e.mjs                 # 527 editor checks, screenshots in /tmp/gm-e2e-*.png
+node tools/seed-e2e.mjs && node tools/e2e.mjs                 # 532 editor checks, screenshots in /tmp/gm-e2e-*.png
 GM_STEPS=20 node tools/e2e.mjs                                # or 1-12, or 6,20 – a subset while working on one step
 ./e2e.sh start [GM_STEPS]                                     # the same run detached, see below
 ./e2e.sh status                                               # live progress, or the last run's result