Upgrade / migrate to UI Kit 2

[riceyrice]

• Created Node 22 Hello World UI Kit 2 app then copied and converted Flagsmith for Jira components back into place
• Upgraded components and hooks to UI Kit 2 and split frontend React components from backend app
• Most backend functionality now accessed by frontend through Forge resolver, except for Jira API accessed by frontend through Forge bridge
• Customised Forge resolver to allow ApiError to be rethrown on client without getting mangled and losing response code
• Added permission checks for backend functionality accessed through Forge resolver
• Changed backend functions which returned undefined to return "" as Forge resolver returns undefined as {} 😡
• Improved error handling in all three UI components
• Refactored issue panel editing as issue actions are no longer available to toggle edit mode: now uses a single multi-select box rather than repeated link/unlink buttons
• Refactored issue panel Flagsmith API calls to work better with UI Kit 2 React
• Fix clashing eslint/prettier clashes between Forge, Visual Studio Code and pre-commit

[Copilot]

Pull Request Overview

This pull request upgrades the application to UI Kit 2 and Node.js 22 while deprecating older components and configurations. Key changes include:

• Updated documentation and decision records to reflect the migration to UI Kit 2.
• Revised README instructions and manifest configuration to use Node.js 22 and native rendering.
• Removed legacy ForgeUI-based components (AppSettingsPage and IssueFlagPanel) and streamlined ESLint and Prettier configurations.

Reviewed Changes

Copilot reviewed 41 out of 49 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
docs/decisions/0004-use-ui-kit-2.md	Introduces the new decision for UI Kit 2 migration.
README.md	Updates Node.js version and CLI installation instructions.
.prettierrc.js	Adds a Prettier configuration with a set print width.
docs/decisions/0002-use-current-forge-runtime.md	Marks the current runtime decision as superseded by UI Kit 2.
flagsmith-jira-app/manifest.yml	Updates runtime configuration and component rendering details.
docs/decisions/0003-use-ui-kit.md	Marks the previous UI Kit decision as superseded by UI Kit 2.
.pre-commit-config.yaml	Removes additional ESLint dependencies to simplify the config.
docs/decisions/0001-use-atlassian-forge.md	Updates the Atlassian Forge decision links and status.
.eslintrc.js	Upgrades ESLint configuration (including React version update).
flagsmith-jira-app/README.md	Adjusts instructions regarding frontend entry points and linting.
flagsmith-jira-app/src/AppSettingsPage.tsx	Removes the legacy ForgeUI-based AppSettingsPage component.
flagsmith-jira-app/src/IssueFlagPanel.tsx	Removes the legacy ForgeUI-based IssueFlagPanel component.

Files not reviewed (8)

• .eslintrc: Language not supported
• .npmrc: Language not supported
• .nvmrc: Language not supported
• .prettierrc.json: Language not supported
• .tool-versions: Language not supported
• flagsmith-jira-app/.gitignore: Language not supported
• flagsmith-jira-app/.prettierrc: Language not supported
• flagsmith-jira-app/package.json: Language not supported

Comments suppressed due to low confidence (3)

.pre-commit-config.yaml:17

• Verify that the removal of additional ESLint dependency entries (such as eslint-loader and related plugins) is intentional and that your CI or local linting workflows are updated accordingly.

-          - [email protected]

flagsmith-jira-app/src/AppSettingsPage.tsx:1

• The entire AppSettingsPage.tsx file is removed; please ensure that all references to this legacy component (such as in routing or the manifest) have been updated as part of the UI Kit 2 migration.

-import ForgeUI, { ... } from "@forge/ui";

flagsmith-jira-app/src/IssueFlagPanel.tsx:1

• The IssueFlagPanel.tsx file has been completely removed; please confirm that its removal is intentional and that any dependent code has been refactored to work with the updated UI Kit 2 components.

-import ForgeUI, { ... } from "@forge/ui";