feat(website): whitepaper block and toast on the form kit; old form CSS removed

[blove]

PR 3 of 3 for docs/superpowers/specs/2026-09-03-lead-forms-system-design.md. The whitepaper signup and the announcement toast compose the form kit; the last of the per-surface form CSS is deleted.

Summary

• WhitePaperForm (the shared component feat(website): homepage restructure (live-stage plan 1 of 3) #1024 extracted, used by the homepage teams block and by WhitePaperBlock on the library pages) rebuilds on the kit: label above the field, inline submit button matching the control height, validation on blur, focus on the field after an invalid submit, failures reported in a failure block, and the direct PDF download link kept. WhitePaperBlock is unchanged from main and keeps rendering the shared form.
• AnnouncementToast composes the same kit in a compact row with the same copy; failures are now reported instead of swallowed.
• chrome.css and landing.css lose the old per-surface form rules; forms.css documents the row-button specificity tie with ui.css (forms.css wins only by import order).
• Specs: an invalid submit never posts; the toast spec proves focus on invalid submit; the teams block spec follows the kit's "Work email" label.

Rebased onto main after #1024 (homepage restructure). The only conflict was WhitePaperBlock.tsx; resolved by taking main's block and porting the kit form into the shared WhitePaperForm with its surface, sourceSection, and idPrefix props, so both call sites get it.

Gates (Task 16, rerun after the rebase)

• Sweep for old form CSS, components, and copy (wp-email-input, Download (free), Email address label): clean. The only earlier hit was the contact-form-growth-disclosure element id inside the kit-based ContactForm from feat(website): contact page on the form kit; enterprise form merges into it #995, which is an id, not retired CSS.
• npx nx lint website: 0 errors, pre-existing warnings only.
• npx nx test website (as CI runs it, from the repo root): pass.
• GROWTH_FORM_POLICY=growth_v1 npx nx build website: pass.
• WEBSITE_E2E_MODE=production GROWTH_FORM_POLICY=growth_v1 npx nx e2e website --grep "whitepaper|landing page|contact page|pricing|footer newsletter|privacy policy|public copy boundary|canonical policy surface": see the latest comment for the rerun result.
• Visual pass before the rebase (dev server, measured via DOM): label above the field, input and button both 44px on one row, error text and focus on invalid submit; contact enterprise intent shows Company and Timeline; pricing renders the enterprise band with no lead form and no overflow; footer input 183px with 36px controls. The toast could not be triggered in the hidden browser pane because its scroll check runs on requestAnimationFrame; it is covered by AnnouncementToast.spec.tsx.

Task 16 Step 5 (manual production gate: one real submission per changed surface, confirm in Neon and PostHog, then delete the synthetic contact) remains after deploy.

🤖 Generated with Claude Code

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Project	Deployment	Actions	Updated
threadplane	Ready	Preview	Sep 6, 2026 1:20am UTC

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[blove]

Rebased onto main after #1024; WhitePaperBlock.tsx conflict resolved by porting the kit form into the shared WhitePaperForm. Gates rerun on the rebased head: lint 0 errors, nx test website pass, prod build pass, production-mode e2e subset (whitepaper, landing page, contact, pricing, footer newsletter, privacy, public-copy gates): 33 passed.

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