This PR does the following:

• Replaces the Webpack-based build pipeline with Vite for Emulsify Core 4.x while preserving legacy upgrade paths.
• Migrates Storybook to React/Vite so Twig-rendered components and React components can be documented in the same Storybook instance.
• Adds a normalized project.emulsify.json environment/config model with platform adapters for generic and Drupal behavior.
• Supports src/components, root ./components, and explicit variant.structureImplementations component structures without requiring existing projects to refactor.
• Preserves Drupal SDC behavior, including Drupal-specific behavior attachment, Twig filter defaults, and component mirroring behind the Drupal adapter.
• Adds first-class Twig Storybook rendering through renderTwig from @emulsify/core/storybook.
• Adds native Twig.js support for Emulsify helpers including bem(), add_attributes(), and switch / case / default / endswitch tags.
• Adds package exports for stable public import paths.
• Adds release-readiness fixtures and CI validation for Vite builds, Storybook builds, mixed Twig/React stories, legacy component structures, and structure implementation variants.
• Updates documentation for the 4.x Vite + Storybook release, including Twig, React, mixed Storybook usage, platform behavior, output paths, and migration notes.
• Keeps Node 24 as the supported runtime floor.

Related Issue(s)

• Release: 4.x (Vite and Storybook React v10)
• ClickUp task

Notes:

• This PR intentionally does not address the hard-coded GitHub URL in Storybook manager styling; that is being handled separately.
• The implemented platform adapters are currently generic and drupal. WordPress + Timber and Craft remain platform directions documented as future adapter opportunities rather than fully implemented adapters.
• Existing lint output still includes pre-existing warnings from the repo-wide ESLint/security rules, but the lint command exits successfully.
• Drupal-specific behavior is now adapter-driven instead of being assumed globally for every Storybook/project type.

Functional Testing:

• Install dependencies with Node 24: npm install
• Run lint: npm run lint
• Run unit tests: npm test
• Build Storybook: npm run storybook-build
• Run release fixture builds: npm run fixtures:release
• Verify package contents include public runtime files: npm pack --dry-run --ignore-scripts --json
• In a Drupal SDC fixture/project, confirm src/components builds into dist and mirrors component output according to Drupal SDC behavior.
• In a generic fixture/project, confirm no Drupal behavior shim or window.Drupal requirement is introduced.
• In Storybook, confirm Twig stories using renderTwig() and React stories render side by side.
• In a Twig story/template, confirm bem(), add_attributes(), and switch / case / default / endswitch render through Twig.js.

Security

Security checks that should be reviewed

• Project structure paths from project.emulsify.json are normalized and unsafe paths outside the project root are ignored.
• Optional project-level Vite and Storybook extension points remain explicit and scoped to the configured project extension paths.
• Drupal behavior attachment is no longer a global assumption for all platforms.
• Package files is allowlist-based so release fixtures/tests are not shipped to downstream installs unless intentionally included.

Accessibility

Should this be checked for this feature?

• Storybook a11y parameters are preserved by default and can still be overridden by project preview configuration.
• This PR primarily changes build/render infrastructure rather than introducing production UI components.
• Mixed Twig/React Storybook rendering should still be reviewed in Storybook for expected semantic markup and addon behavior where project stories include user-facing UI.