TypeScript: Convert ConfirmStep.jsx to TSX and remove any types in Import flow

[andrejvysny]

Context
Issue #38 calls for TypeScript strictness and comprehensive types. The repo has strict: true, but there is a JavaScript file: resources/js/components/Import/ConfirmStep.jsx, and many any usages in Import types and FieldMappingService.

Scope

• Convert resources/js/components/Import/ConfirmStep.jsx to ConfirmStep.tsx with proper props interfaces
• Replace any in FieldMappingService signatures and internals with typed structures using existing types (ImportFailure, Import) and new helper types where needed
• Add/extend types in resources/js/types/index.ts for import mapping and field definitions if gaps exist

Affected files

• resources/js/components/Import/ConfirmStep.jsx -> ConfirmStep.tsx
• resources/js/pages/import/FieldMappingService.ts (reduce any usage)
• resources/js/types/index.ts (add missing types)

Acceptance criteria

• No remaining any/unknown escape hatches in targeted files (except intentional unknown)
• tsc --noEmit passes
• Unit tests updated/added if needed
• Link back to P3: Optimize Frontend Architecture and Performance #38

Labels
area:frontend, area:types, type:refactor