docs: hand the landing-page role from the README to maka.apache.org

[Astro-Han]

Summary

Since #4660 the website is the landing page and the downloads path, but both READMEs still ran 290 lines as landing page, install guide and architecture summary, and opened with a different sentence from the site and the repository description.

• README.md, README.zh-CN.md and the .asf.yaml description carry the sentence settled in [DISCUSS] Rebuild the Maka website and project narrative #4307. The header is title, badges and hero; the hero carries the headline, so the sentence and lede appear once, as text opening "What Maka is". That section replaces "Why Maka", "Surfaces" and "Current capabilities" with the site's four claims (measured not claimed, the log is the runtime, your machine and your model, one Runtime Host) and a sentence linking the site and ARCHITECTURE.md. "Releases and downloads" becomes "Get Maka" with the same three labelled paths as the downloads page and links there instead of to GitHub Releases. Requirements, start and first run move under "Build from source". Website and Downloads are badges in the style of the row above them. The rest of the README is unchanged apart from a website/ line in the layout and a website link in Documentation. Both languages stay section-for-section identical.
• The hero is rendered from the website itself: website/scripts/readme-hero.mjs (run with npm --workspace @maka/website run readme-hero) builds the site and screenshots the homepage headline and RuntimeEvents scene per language and colour scheme into .github/assets/readme-hero.*.png, and the READMEs pick light or dark with a <picture> element. The two per-language illustrations that baked in the old tagline are removed, and docs/code-origin-audit.md now records that the heroes are renders of the site's own copy and styles rather than generated art.
• Every retained claim was checked against the repository. Three were stale and are corrected: Desktop Nightly has published macOS arm64 and x64, Windows x64 and Linux x64 and arm64 builds for some time, but the README and the website's three platform lines said Apple Silicon only with a Windows preview, so both now name the full matrix with Windows and Linux as unsigned previews; ARCHITECTURE.md links four deep dives, not six, so the README stops counting; and the repository layout gains native/, skills/, patches/ and experiments/.
• website/test/site.test.mjs asserts the two READMEs and the description carry the sentence, and the CI planner runs the website workspace for a README change so the check runs when it matters. .asf.yaml keeps its existing release-contract lane.
• Committing the first version of this branch showed that the pre-commit Biome check from feat(ci): add fast local validation hooks #4132 could not commit a binary or a Markdown file: it pipes every staged blob through git show and Biome with Node's default 1 MiB buffer, Biome rejects stdin that is not UTF-8, and for a language it parses without formatting it echoes nothing, which the hook read as unformatted. Binaries are now skipped by git's NUL-byte heuristic, an empty echo is treated as no handler, and the buffer limits are lifted, with a test for each.

Fixes #4684

Verification

• npm --workspace @maka/website run test:dist: 9/9, including the new cross-surface sentence test.
• npm --workspace @maka/website run readme-hero: writes the four PNGs above from the built site.
• node --test scripts/ci-test-plan.test.mjs scripts/ci-workflow-policy.test.mjs scripts/biome-staged-check.test.mjs: 80/80. The new planner test and the hook's binary and Markdown cases fail on main; the first two commit attempts of this branch failed on exactly those two hook paths.
• npm run format, npm run lint, npm run check:asf-headers: clean.
• Scripted check that every relative link and image path in both READMEs exists and the two in-page anchors match a heading; both files have the same 13 headings in the same order.

AI use

Select exactly one:

• No generative tool made a substantive contribution
• Generative tooling made a substantive contribution

Tool(s) and scope: Claude Code set the section skeleton, wrote the render script, the tests, the planner and hook changes and this description; Gemini 3.8 Flash (Antigravity CLI) drafted the README prose from that skeleton, which I then corrected against the site copy and cut back to bullets. I reviewed every line of both READMEs.

Checklist

• Tests cover the change and fail without it
• Lint, format, typecheck and the affected suites pass locally

Does this PR entail a change in behavior?

• Yes — described under Summary above
• No