Enhance default userEvent.keyboard fallback mechanism

[Romulad]

Describe the feature you'd like:

Current behavior

The current implementation of userEvent.keyboard parses input and looks up a mapping in keyMap.ts:

• Special interactions (e.g. [Enter]) use the code field
• Regular characters use the hex field
• When no mapping is found, it falls back to:

{ code: descriptor, hex: "Unknown" }

This value is then written to the process via stdin.write.

Problem

When a character is not mapped, the fallback "Unknown" is written to output.
For example:

userEvent.keyboard('https://google.com');

Produces:

httpsUnknownUnknownUnknowngoogle.com

Instead of:

https://google.com

My suggestion

Instead of falling back to:

{ code: descriptor, hex: "Unknown" }

Fallback to:

{ code: descriptor, hex: descriptor }

This would allow unmapped characters to pass through directly to stdin.write.

Why this approach

• Supports a much wider range of characters without requiring explicit mappings
• Reduces maintenance overhead of manually updating the key map
• Leverages Node.js native handling of character input instead of re-implementing it
  At the same time:
• Special interactions (e.g. [Enter]) would still rely on explicit mappings
• The [] syntax remains reserved and deterministic for non-text interactions

Suggested implementation:

• Change the fallback behavior to use the raw descriptor instead of "Unknown"
• Keep explicit mappings for special keys
• Ensure [] syntax remains strict and reserved for special interactions

Describe alternatives you've considered:

Teachability, Documentation, Adoption, Migration Strategy: