SEO: static platform CTAs and stronger homepage discovery

[masarray]

Goal

Move the highest-value landing-page improvements from the SEO audit into a low-risk, regression-guarded change set.

Changes

• Keep both Windows and macOS hero download CTAs in static EN/ID HTML instead of creating the Mac CTA at runtime.
• Preserve the safe #download Mac fallback and keep the existing manifest runtime responsible only for upgrading it to the reviewed macDmgUrl.
• Make the mobile sticky CTA platform-neutral (Choose download / Pilih unduhan) so a Windows-only installer is never implied while the bar says Windows + macOS.
• Add direct, crawlable homepage links to Stereo Enhancer, Vocal Enhancer, Mix Bus and Mastering workflow pages in both languages.
• Remove the now-unnecessary Mac CTA DOM-construction code from the lightweight loader.
• Strengthen the P0 validator so CI fails if static Mac/Windows CTAs, neutral mobile routing, DMG binding/fallback, Mac styling, release manifest support, or direct workflow links regress.

Deliberately unchanged

• No title/meta/canonical/hreflang/site-name schema changes.
• No release binaries or release.json changes.
• No CSS redesign or bundling changes in this PR.
• No sitemap restructuring in this PR.

Keeping CSS/build pipeline and sitemap architecture out of this PR is intentional: those are higher blast-radius performance/discovery changes and should be measured separately after this structural landing pass is proven stable.

Regression policy

Do not merge unless the existing Pages validation suite passes. Pull-request jobs cannot deploy, so this PR is validation-only until merge.

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: dbbb9def4d

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[chatgpt-codex-connector]

Bind the fallback assertion to the Mac CTA

If mac-dmg-link-hero is changed to an incorrect or external URL, this validation still passes because each landing page contains several unrelated href="#download" links and the three substrings are checked independently across the whole document. Parse the anchor or otherwise assert that this specific ID has the fallback so the intended download-routing regression is actually detected; the Indonesian predicate has the same issue.

AGENTS.md reference: AGENTS.md:L127-L129

Useful? React with 👍 / 👎.