fix(media): folder creation now triggers on Enter key in media picker

[ronstarling9]

Problem

• Folder creation in media picker breadcrumb only triggered on blur
• Enter key had no effect, requiring mouse click or tab away
• Regression from Umbraco v13 where Enter key worked

Solution

• Added keyboard event handler to uui-input element
• Enter key now triggers folder creation immediately
• Escape key cancels folder creation (improved UX)
• Maintains backward compatibility with blur behavior

Testing Performed

• Build successful
• TypeScript compilation clean
• Added both Enter and Escape key handlers

Fixes #20594

[github-actions]

Hi there @ronstarling9, thank you for this contribution! 👍

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