feat: add Storybook stories for pure components

[talissoncosta]

Context

Spike #7097 audited Storybook component coverage and identified which components can be added today. This issue tracks the implementation.

What

Add Storybook stories for 39 components that can render in isolation, organised into sidebar categories. Fix components where trivial dependency changes unblock Storybook rendering.

Stories (39 components, 8 categories)

Category	Components
Forms	Button, ButtonDropdown, Checkbox, CheckboxGroup, GhostInput, Radio, Switch
Feedback	Banner, EmptyState, InfoMessage, Loader, WarningMessage
Navigation	Breadcrumb, NavSubLink, SidebarLink, Tabs
Layout	AccordionCard, Card, FormGroup, PageTitle, Panel, Row
Data Display	BooleanDotIndicator, ClearFilters, Confidence, DropdownMenu, IdentifierString, LabelWithTooltip, Logo, SettingTitle, StatItem, ToggleChip, Tooltip, VCSProviderTag
Modals	Modal (Alert, Header, CloseButton), ModalDefault
Patterns	SettingRow, Skeleton
Icons	Icons catalogue

Component fixes required

• Remove `@ionic/react` IonIcon from InfoMessage, AccordionCard, IdentifierString, StatItem
• Remove dead `enabledButton` prop from WarningMessage
• Add explicit imports for window globals (Panel, PageTitle, LabelWithTooltip, ToggleChip)
• Inline trivial Utils functions (Checkbox, Confidence, Tabs)
• Extract `tagColors` from Constants to standalone file
• Extract Loader from `project-components.js`

Storybook infrastructure

• Webpack mocks for CommonJS modules (`code-help`, `_data.js`, `dompurify`)
• Global registration in `preview.js` (Tooltip, Row, FormGroup)
• Unit tests for extracted functions

Remaining blocked (13 components)

Tracked in Storybook Coverage Report. Root cause: `constants.ts` uses relative `require()` for code-help files. Needs #6310 to unblock.

PR

#7100