Paste handling only trims whitespace at start/end, not inside the pasted code

[ranielison]

When pasting a code into PinCodeTextField, the package already applies a normalization step to remove unwanted spaces from the pasted value. However, this normalization only trims whitespace at the beginning and end of the string.

In some real-world scenarios (e.g. copying codes from SMS, email clients, or messaging apps), the pasted code may contain spaces in the middle, such as:

"12 34 56"

Currently, this results in the internal spaces being preserved, which breaks the expected behavior for PIN / OTP inputs that require a continuous numeric string.

After checking the source code, I found that the current implementation only uses a trim()-like approach, which does not handle inner whitespace.

Expected behavior

All whitespace characters should be removed from the pasted value, including those inside the string, so that:

"12 34 56"

becomes:

"123456"

Additional context

This behavior is especially important for OTP / verification code flows, where users often paste codes from external apps that may introduce spaces automatically.