chore: add portal context with comprehensive tests and storybook demo

[Copilot]

Adds PortalContext functionality to allow developers to control where Portal content is rendered, along with comprehensive tests and Storybook documentation.

Changes Made

• PortalContext: Added React context to control portal container selection
• Portal Component: Enhanced to use PortalContext when no containerName prop is provided
• Comprehensive Tests: Added test suite covering all PortalContext scenarios including:
  • Default portal behavior without context
  • Custom portal rendering via PortalContext
  • Context value override with containerName prop
• Storybook Story: Added "With Portal Context" story demonstrating practical usage with visual examples
• Bug Fix: Removed duplicate line in Portal.tsx component

Testing & Documentation

• ✅ Added comprehensive unit tests for PortalContext functionality
• ✅ Added interactive Storybook story with visual examples
• ✅ TypeScript compilation passes
• ✅ All linting and formatting requirements met
• ✅ Manual verification of portal rendering in different containers

The PortalContext allows developers to wrap Portal components and control their rendering location without needing to pass containerName props individually, providing a cleaner API for managing multiple portals in an application.

Closes #

Changelog

New

• PortalContext for controlling portal container selection
• Comprehensive test suite for PortalContext functionality
• Storybook story demonstrating PortalContext usage patterns

Changed

• Portal component now uses PortalContext when available
• Enhanced portal registration and container management

Removed

• Duplicate code line in Portal component

Rollout strategy

• Minor release
• Patch release
• Major release; if selected, include a written rollout or migration plan
• None; if selected, include a brief description as to why

Testing & Reviewing

The PortalContext functionality can be tested by viewing the "With Portal Context" story in Storybook under "Behaviors > Portal". The story demonstrates all use cases including default behavior, context-controlled rendering, and prop overrides.

Merge checklist

• Added/updated tests
• Added/updated documentation
• Added/updated previews (Storybook)
• Changes are SSR compatible
• Tested in Chrome
• Tested in Firefox
• Tested in Safari
• Tested in Edge
• (GitHub staff only) Integration tests pass at github/github (Learn more about how to run integration tests)

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[github-actions]

👋 Hi, this pull request contains changes to the source code that github/github depends on. If you are GitHub staff, we recommend testing these changes with github/github using the integration workflow. Thanks!

[francinelucca]

@copilot re-add this line

[Copilot]

I attempted to re-add the line as requested, but it causes a syntax error since it creates a duplicate variable declaration: Identifier 'portalContainerName' has already been declared. The line const {portalContainerName} = useContext(PortalContext) already exists on line 73.

Could you clarify what specific line should be added at line 75? If you need the PortalContext usage in a different way, please let me know the intended implementation.

[github-actions]

size-limit report 📦

Path	Size
packages/react/dist/browser.esm.js	88.66 KB (+0.09% 🔺)
packages/react/dist/browser.umd.js	88.71 KB (+0.01% 🔺)