size: dedupe width/height spelling and extend the name-table pack to dictionary keys

Source (both help every build):
- save() no longer re-spells x/y/width/height/mipLevel when forwarding to
  readTexture — readTexture derives the identical defaults from opts itself;
  only the forced Ctor override remains ({ ...opts, Ctor: U8 }).
- resizeCanvas builds its return value through sz(), so the width/height keys
  outside sz are spelled one less time ({ ...sz(width, height), changed }).

Build (pack-gated, so gzip-delivered builds are untouched):
- The name-table pack gains a second candidate class, KEY_CANDIDATES:
  dictionary keys (width, height, format, usage, …) that the member-only pass
  must refuse. They are aliased in both positions — .name → [$x] and name: →
  [$x]: — because a computed key evaluates to the identical string, so the
  descriptor the browser sees never changes. A string mask (new maskStrings,
  sharing mapTemplateText's walk) proves no rewrite can land inside a string
  or template literal, and any occurrence that is neither shape disqualifies
  the name for that build.
- Pack selection is now price-then-apply: every candidate is priced against
  its own table-slot cost, and the set as a whole must clear the fixed
  let[]="".split(",") skeleton — previously uncharged, which let a lone
  marginal name pack at a net code loss. The legend comment's size is now
  logged where it is appended (it is documentation on its own line, not code).

Code line: bare tiny -20B, full-featured tiny -102B, min -46B. Files with
packComment on grow ~1-2B from the longer legend; packComment: false keeps
the whole saving.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FrkUU5GGyzvhujesWXZt1k

Author: claude

dist/tinywebgpu.min.js

@@ -706,7 +706,8 @@ ${main}
         width = fit(canvas.clientWidth, canvas.width), height = fit(canvas.clientHeight, canvas.height),
         changed = canvas.width !== width || canvas.height !== height,
         changed && (canvas.width = width, canvas.height = height),
-        { width, height, changed }),
+        // sz spells the width/height keys once for the whole library — reuse it here too.
+        { ...sz(width, height), changed }),
     } : {}),
 
     ...(F_SHOW ? {
@@ -760,7 +761,10 @@ ${main}
         if (!/^(rgba|bgra)8unorm(-srgb)?$/.test(tex.format))
           err(19, MSG && `save: needs an 8-bit RGBA texture, got '${tex.format}'. Render it into an rgba8unorm target first.`);
         let [width, height] = texWH(tex, opts);
-        let px = await S.readTexture(tex, { x: opts.x, y: opts.y, width, height, mipLevel: opts.mipLevel, Ctor: U8 });
+        // readTexture derives the same x/y/width/height/mipLevel defaults from `opts` itself;
+        // save's extra keys (type, quality, download) are ignored there, and Ctor spread last
+        // always wins, so the pixels come back as bytes whatever the caller passed.
+        let px = await S.readTexture(tex, { ...opts, Ctor: U8 });
         // ImageData is RGBA; the canvas format is BGRA on most platforms, so swap the ends.
         if (tex.format.startsWith('bgra'))
           for (let i = 0; i < px.length; i += 4) { let b = px[i]; px[i] = px[i + 2]; px[i + 2] = b; }