Core block recipes and validation updates

Contract change type: additive

Added

• Core quote and pull-quote blocks follow the spectre-ui sp-quote recipe
  on the front end and in the editor, with two registered block styles:
  Accent rule (thick accent leading edge) and Statement (large text
  under a decorative quote mark). Bold text in the citation renders as the
  name; the rest renders muted as role and organization. The accent colour
  comes from theme.json settings.custom.quote.accent
  (--wp--custom--quote--accent), so a child theme re-points it without
  redeclaring a --sp-* property.
• Core table blocks follow the sp-table recipe, including the header row,
  caption, footer row, and the Stripes style. Computed styles match an
  sp-table with the same data.
• README.md "Core Block Styles" and a Child Themes table pointing at the
  component options (sp-text weight/leading/variant="accent",
  accent/accentOutline buttons, sp-stepper tone, sp-quote,
  sp-stat, split sp-section-head, sp-table) that replace styling
  [data-sp-text-native] or .sp-btn internals.

Fixed

• Post content inside sp-prose now follows the layout.prose.flow rhythm
  (wider gaps around headings, quotes, figures, and rules). The unlayered
  sp-content-flow 16px gap overrode it before, and core's figure and
  pull-quote margins plus spectre-ui 5.5.0's .sp-prose blockquote margin
  reset would otherwise collapse quote and figure spacing.
• Removed the argument-less editor-color-palette and editor-font-sizes
  theme supports. theme.json already supplies both, and WordPress 7.1
  printed a foreach() warning for them.

Changed

• ESLint ignores built JavaScript bundles copied into nested downstream child
  themes. Those minified outputs are linted from source in their owning
  repositories and otherwise produce false errors when validating this repo.
• Updated Vite from 8.3.3 to 8.3.4.
• Raised the Node.js engine floor to >=24.18.0 to match the WordPress
  Playground runtime pulled in by @wordpress/env, which otherwise emits
  EBADENGINE warnings on install. CI and the WordPress smoke test now run on
  Node 24 only.