a11y: associate shared Input and Select labels with their controls

[McanKul]

Goal

Make the shared Input and Select labels programmatically associated with their controls.

Acceptance criteria

• Generate a stable ID with useId when neither an explicit ID nor suitable name is provided.
• Each label.htmlFor matches its control ID.
• Explicit IDs and existing name behavior remain supported.
• Adjacent controls receive unique IDs.
• Add focused render tests for both components.

Files

• src/components/ui/Input.tsx
• src/components/ui/Select.tsx
• New src/components/ui/FormControls.test.tsx

Verification

• npm test -- src/components/ui/FormControls.test.tsx
• npm run typecheck