chore: fix unsafe type assertions in Custom Sounds components

Issue Description

Description
In the Custom Sounds administration views (AddCustomSound.tsx and EditSound.tsx), there are multiple // FIXME comments marking unsafe type assertions (as any) and any typed parameters. This bypasses TypeScript's safety checks and can lead to potential runtime errors.

Affected Files:

• client/views/admin/customSounds/AddCustomSound.tsx: soundFile parameter is typed as any
• client/views/admin/customSounds/EditSound.tsx: sound parameter is typed as any
• client/views/admin/customSounds/lib.ts: Missing optional property in type definition causing type mismatch

Goal
Refactor the components to use proper TypeScript types (e.g., File and union types) and remove the unsafe assertions.

Proposed Solution

• Type AddCustomSound state and handlers as File
• Use union type EditSoundProps['data'] | File in EditSound with proper type narrowing (instanceof File)
• Ensure validate and createSoundData utility functions accept the correct types

Start by reading the FIXME-marked assertions and parameters in client/views/admin/customSounds/AddCustomSound.tsx and EditSound.tsx, then inspect the related type definition and utilities in client/views/admin/customSounds/lib.ts. Done means the affected state, handlers, validate, and createSoundData usage have proper TypeScript types without unsafe assertions or any parameters.