perf: slim down SolidElement base class to reduce bundle size

[AaronWeber90]

Title: [skip chromatic] perf: slim down SolidElement base class to reduce bundle size

Description:

• Removed rarely-used features from the SolidElement base class (inherited by all 59 components) and moved them to opt-in modules, significantly reducing the bundle size for consumers who import individual components.

What changed:

• Removed dir and lang reactive properties (unused by any component; native HTML attributes still work)
• Removed token() method and animate.ts import — moved to standalone token() utility in src/internal/token.ts (used by 3 components: tag, video, audio)
• Removed onThemeChange lifecycle hook — moved to self-managed listeners in the 2 consuming components (icon, audio)
• Removed CSS @import for interactive.css, headline.css, paragraph.css — moved to importable modules in src/internal/shared-styles.ts (only added by the ~14 components that actually use them)
• Updated Storybook Vite config to process the new shared-styles.ts file with Tailwind

What remains in SolidElement:

• Tailwind --tw-* CSS variable resets (needed by all components)
• box-sizing reset and [hidden] rule
• emit() method (used by 20+ components)

Definition of Reviewable:

• Documentation is created/updated (no public API change — internal refactor only)
• Migration Guide is created/updated (no breaking change — dir/lang were unused, other features moved to opt-in imports)
• E2E tests (features, a11y, bug fixes) are created/updated
• Stories (features, a11y) are created/updated (no new features or visual changes)
• relevant tickets are linked

Closes #2971

[changeset-bot]

🦋 Changeset detected

Latest commit: 7a18277

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
@solid-design-system/components	Minor
@solid-design-system/styles	Minor
@solid-design-system/tokens	Minor

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