feat(ui): add landing stats band, align hero & steps to redesign

[fullstackjam]

Summary

Reconciles the site with the latest OpenBoot Redesign design file (imported from Claude Design). The redesign was ~95% already in place from #25; this closes the remaining gaps, concentrated on the landing page, plus minor polish elsewhere. Product features that exist beyond the static mock (docs search + collapsible nav, dashboard import/share modals, loading/empty states, config-detail Share button + extra package sections) are intentionally preserved — not stripped to match a static mockup.

Landing (src/routes/+page.svelte):

• Hero eyebrow → bordered pill badge with a pulsing dot + v0.44 version chip
• New 4-up stats band; the star count is wired to the live /api/github/stars endpoint (shows the real count, consistent with the header) rather than a hardcoded number
• Reworked "how it works" from bordered cards → the design's borderless ghost-number + divider treatment, with tightened copy
• Hero title up to 4rem / -0.045em; added the ob-pulse keyframe

Polish:

• explore: skeleton-card radius 16→12px; CTA description trailing period
• editor: inactive preset background token → --bg-secondary; script textarea min-height 200→148px; "✎ editable" affordance on the post-install.sh header
• config detail: removed the stray DNA-segment border-radius (design segments are square)

Test plan

• npm run validate passes (lint + type-check + tests + build)
• Landing verified in dark and light themes via Playwright — matches the design's variants
• Diff is surgical — every changed line traces to the design (no repo-wide reformatting)

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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