theme: export color metadata and sync docs

[geoquant]

Summary

• export shared theme metadata from @cloudflare/kumo and switch registry/Figma consumers to use it instead of scraping semantic colors from CSS
• make the colors docs page data-driven from package metadata, remove stale token/theme guidance, and add concise token authoring docs without redesigning the page
• keep generated light-dark() theme registration for semantic utility compatibility, while continuing to use explicit [data-mode] scoped variables to prevent flicker
• ban raw light-dark(...) and var(--color-...)/var(--text-color-...) usage inside component class strings so token usage stays lint-enforced

Toast Token Decision

We found raw class-string color values in packages/kumo/src/components/toast/toast.tsx:

• old error: light-dark(var(--color-red-600), var(--color-red-400))
• old warning: light-dark(var(--color-amber-700), var(--color-amber-500))

For this PR, we intentionally switched to the nearest existing semantic tokens instead of introducing new ones:

• new error: text-kumo-danger -> red-500 light / red-400 dark
• new warning: text-kumo-warning -> yellow-800 light / yellow-400 dark

This keeps component code on semantic tokens and lets lint enforce the rule. If design wants exact parity with the prior toast colors, the follow-up should add dedicated tokens in packages/kumo/scripts/theme-generator/config.ts rather than reintroducing raw values in component classes.

Verification

• pnpm --filter @cloudflare/kumo codegen:themes
• pnpm --filter @cloudflare/kumo typecheck
• pnpm --filter @cloudflare/kumo exec vitest run scripts/theme-generator/generate-css.test.ts scripts/component-registry/utils.test.ts tests/imports/package-json-validation.test.ts tests/lint/no-primitive-colors.test.ts
• pnpm --filter @cloudflare/kumo lint
• pnpm --filter @cloudflare/kumo build
• pnpm --filter @cloudflare/kumo-docs-astro typecheck
• pnpm --filter @cloudflare/kumo-docs-astro build
• pnpm --filter @cloudflare/kumo-figma typecheck
• pnpm --filter @cloudflare/kumo-figma validate

[pkg-pr-new]

npm i https://pkg.pr.new/@cloudflare/kumo@226

commit: 4882d7d

[github-actions]

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Commit: 4882d7d

[github-actions]

Visual Regression Report

8 screenshot(s) with visual changes:

Button / Icon Only

9,697 px (3.57%) changed

Before	After	Diff

Button / Loading State

6 px (0%) changed

Before	After	Diff

Button / Disabled State

2,793 px (1.12%) changed

Before	After	Diff

Dialog / Basic Dialog

96,424 px (1.84%) changed

Before	After	Diff

Select / Basic Usage

14,234 px (2.57%) changed

Before	After	Diff

Select / Loading

0 px (0%) changed

Before	After	Diff

Select / Select.Option

19,481 px (2.27%) changed

Before	After	Diff

Select (Open)

0 px (0%) changed

Before	After	Diff

19 screenshot(s) unchanged

• Button / Variants
• Button / Sizes
• Button / With Icon
• Dialog / Alert Dialog (role="alertdialog")
• Dialog / Confirmation Dialog (with disablePointerDismissal)
• Dialog / With Actions
• Dialog / With Select
• Dialog / With Combobox
• Dialog / With Dropdown
• Dialog (Open)
• Select / Without Visible Label
• Select / With Description and Error
• Select / Placeholder
• Select / Label with Tooltip
• Select / Custom Rendering
• Select / Multiple Item
• Select / Multiple with Custom Indicator
• Select / More Example
• Select / Select

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Generated by Kumo Visual Regression

[geoquant]

Reviewed the branch again after fixing the docs copy mismatch.

A few files in this PR are not core to the color/theme/metadata change, but I left them in intentionally for observability rather than hiding them:

• packages/kumo-docs-astro/src/components/SearchDialog.tsx
  • adds runtime validation for the fetched component registry shape
  • this came up while keeping docs typecheck / feedback loops green
• packages/kumo-docs-astro/src/components/demos/TabsDemo.tsx
  • fixes render-prop anchor content in the demo
  • unrelated to colors, but surfaced during docs feedback-loop cleanup
• packages/kumo-figma/src/generators/select.ts
• packages/kumo-figma/src/generators/drift-detection.test.ts
  • small figma validation / drift-detection fixes needed while touching the figma token pipeline
• packages/kumo/src/code/provider.tsx
• packages/kumo/src/code/server.tsx
  • lint-suppression cleanup only

Happy to remove / split any of those if reviewers want the PR to stay narrower.

Also: I rebuilt the Figma plugin locally while checking the stale-runtime concern. packages/kumo-figma/src/code.js is still gitignored by repo convention, so it is not part of the PR diff, but local build output now matches the metadata-driven source.