feat(verification): add MediaUploadStep with drag-and-drop, file preview, and upload progress

[laurentketterle-hub]

Summary

Implements the MediaUploadStep component for the verification wizard — a polished, accessible drag-and-drop file upload UI built with React Dropzone and Tailwind CSS.

✨ Features

Feature	Details
Drag & Drop	Full drag-and-drop zone with visual active state (blue highlight + scale)
Click to Select	Click on drop zone or press Enter/Space to open file dialog
Image Preview	Auto-generated thumbnails for image files
Video Preview	Video thumbnails with play overlay for video files
Upload Progress	Simulated progress bar with percentage indicator and "Upload complete" badge
File Validation	Configurable max file size, empty file rejection, error display
Multiple Files	Optional multiple prop for multi-file uploads
Controlled Mode	Accept external files prop with onFilesChange callback
Dark Mode	Full Tailwind dark mode support with dark: variants
Accessibility	ARIA roles (button, list, listitem, alert, progressbar), keyboard navigation, labels
File Removal	X button to remove files with proper cleanup of object URLs

🎨 Screenshot Description

• Drop Zone: Centered card with upload icon, label text, and hint — switches to "Drop files here…" on drag with blue border and subtle scale animation
• File Card: Shows thumbnail (image/video preview or file type icon), file name, size in human-readable format, category badge (Image/Video/PDF/Document), progress bar during upload, green checkmark on completion
• Error State: Red banner with alert icon for size/validation errors

🧪 Tests

24 test cases in MediaUploadStep.test.tsx covering:

• Rendering with default and custom labels
• Keyboard accessibility (Enter, Space, Tab)
• Click-to-select file dialog trigger
• Drag-and-drop with visual active state
• Image and video preview rendering
• File size formatting (B, KB, MB)
• Category badge display
• File removal with object URL cleanup
• Upload progress bar and completion badge
• Size validation (too large, empty)
• Single vs multiple file modes
• Controlled component mode
• Custom accept types
• ARIA attributes (alert, list, listitem, progressbar)

📂 Files Changed

• frontend/features/verification/components/steps/MediaUploadStep.tsx — new component (~290 lines)
• frontend/features/verification/components/steps/__tests__/MediaUploadStep.test.tsx — test suite (~350 lines)

🔗 References

Closes #422

[vercel]

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[Tybravo]

@laurentketterle-hub good work done