Implement helperText tooltip placement in FormField

[nfdiop]

Summary

• Implement the helperTextPlacement: "tooltip" option for form fields — renders an info icon next to the label that shows helperText in a tooltip on hover/focus
• When helperTextPlacement is "bottom", renders helper text below the field (existing behavior)
• Default placement is "tooltip" (matching the @default in FormFieldApi.ts)
• Uses the existing Tooltip component from base-components/tooltip
• Adds --osdk-form-label-row-gap, --osdk-form-info-icon-size, --osdk-form-info-icon-color CSS tokens

Test plan

• Bottom placement renders helper text below the field
• Tooltip placement renders info icon trigger (not bottom text)
• Default placement (omitted) renders info icon
• Absent helperText renders neither icon nor bottom text
• Typecheck passes
• All existing tests still pass
• Manual visual testing in storybook/sandbox

[github-actions]

size-limit report 📦

Path	Size	Change
@osdk/api	432 B	0%
@osdk/client	26.42 kB	0%
@osdk/oauth	6.52 kB	0%
@osdk/react	513 B	0%
@osdk/react/experimental	52.44 kB	0%
@osdk/react/experimental/admin	2.43 kB	0%
@osdk/react-components	10 B	0%
@osdk/react-components/experimental	481.27 kB	-0.05% 🔽
@osdk/react-components/primitives	40.46 kB	0%
@osdk/widget.client-react	10.56 kB	0%