feat(landing): add 0.14.0 and 0.15.0 release blog posts (+ i18n audit fixes) (#5704)

* feat(landing): add 0.14.0 and 0.15.0 release blog posts

Cover the two most recent minor releases the blog was missing:
0.14.0 "Inspiration Time Machine" (plan mode, HTML version history,
design-system source context, model cost tiers) and 0.15.0 "Cost Less.
Ship Faster." (a leaner Design System Prompt — 49.5% faster to first
token, decks that drive like a workspace, website clone from a URL).

Each post follows the established release-note format: English body,
per-locale bodyHtml for all 10 shipped non-English locales, and cover
plus inline feature illustrations in the site's line-art house style.

* fix(landing): repair blog localization gaps found in an audit

A full-blog i18n audit surfaced pre-existing gaps in the localized
bodies (localizedBodyHtml fully replaces the Markdown body, so any gap
is invisible to English readers but real for everyone else):

- osaka-kyoto-meetup was English-only — add full 10-locale i18n.
- 0.9.0 translations dropped the inline figure the English body has —
  restore it (localized figcaption) in all 10 locales.
- what-is-vibe-design, vibe-design-tools/-vs-/-with-stitch, and
  open-source-alternative had their translated headings one level too
  deep (## rendered as h3/h4) — normalize to match the English levels.

* style(landing): restyle 0.14.0/0.15.0 release art to warm editorial covers

The two new release posts shipped with the near-white line-art cover
style, which clashed with the warm editorial illustration covers used by
the rest of the recent blog cluster on the index. Regenerate both
covers and their inline feature figures in the warm sage-green editorial
style so the blog index reads as one consistent set, and update the
figure alt text to match the new artwork.

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Co-authored-by: Joey <236967869+joeylee12629-star@users.noreply.github.com>

Author: joeylee12629-star