feat(webkit): add the marketing component category

[gabriel-lisboa-azion]

Summary

• Umbrella for the marketing component category: registers the category and gathers every marketing component PR (feat(webkit): add the texture-material marketing component #991–feat(webkit): add the sticky-stack marketing component #1020 and follow-ups) so the whole set can be reviewed and validated against main in one place.
• Adds Illustration (a closed registry of official scenes shipped as plain SVG assets, loaded on demand) and the marketing asset base: agent marks (@aziontech/webkit/assets/agents/*.svg), analyst logos (@aziontech/webkit/assets/logos/*.svg) and brand marks under svg/brands.
• Theme adds only what marketing uses (texture-wave-a/b, brand-marquee); the size gate learns entryOnly, so a code-split entry is budgeted on its initial chunk.

How to test

1. pnpm --filter theme run build:tokens → no dist diff; the only new animations versus main are --animate-texture-wave-a/b and --animate-brand-marquee.
2. cd packages/webkit && npx vitest run src/components/content/illustration → 39 tests pass, one render per registered scene.
3. node scripts/check-size.mjs → illustration ≈ 1.4 KB of 2 KB, "initial chunk only, 23 async chunk(s) excluded"; every other entry within budget.
4. pnpm storybook:dev → Components/Content/Illustration and Foundations/Illustration System show every scene plus the placeholder, light and dark.
5. In a consumer, import claude from '@aziontech/webkit/assets/agents/claude.svg' resolves to a URL that renders in an <img>.

Notes

• Draft: marketing sub-PRs merge into this branch first; it opens for review once they land.
• Verified locally with every marketing sub-branch and the open webkit PRs merged together: lint, type-check, type-coverage, authoring, test gate, size, catalog, story-source, 2947 tests and the Storybook build all pass.
• The category registration (.claude/**, .specs/_schema.json, .specs/_template.md) ships separately in chore(agents): register the marketing category and add the containers guide #1039; the changes are identical, so the two merge cleanly in either order.