Closes #8635 (settings pages scope)

Went through all the settings-related pages and replaced antd components with their @highlight-run/ui equivalents. Here’s what changed:

Direct antd imports removed:

• AutoJoinForm — antd Checkbox → SwitchButton, antd Tooltip wrapper → UI Tooltip
• GitHubSettingsModal — antd Select → ComboboxSelect
• GitHubEnhancementSettingsForm — antd Select → ComboboxSelect

Antd wrapper components replaced:

• WorkspaceSettings — @components/Alert (antd wrapper) → Callout
• FieldsForm — @components/Input (antd wrapper) → native <input>, legacy Button → @components/Button
• DangerForm — same Input + Button migration
• ErrorSettingsForm — @components/Select (antd wrapper) → UI Select with creatable/tags mode
• ErrorFiltersForm — same Select migration

After these changes, the workspace settings, project settings, and team management pages have zero direct antd imports. The remaining antd wrapper usages (ExcludedUsersForm’s Select with dynamic search + custom render) are more involved and could be a follow-up.

I tested the component swaps locally to make sure the interactive behavior (tag creation, search filtering, switch toggle) works as expected.

/claim #8635