feat: make variable values more accessible with copy button

[musabrayan]

Description

This pull request adds a copy-to-clipboard button beside each environment and runtime variable name. It allows users to easily copy the variable’s value without surrounding quotes. A toast message confirms the copy action.

It improves the UX by making values more accessible and aligns with issue #4926.

Contribution Checklist:

• The pull request only addresses one issue or adds one feature.
• The pull request does not introduce any breaking changes
• I have added screenshots or gifs to help explain the change if applicable.
• I have read the contribution guidelines.
• Create an issue and link to the pull request.

Issue reference: Closes #4926

Screenshots

Before	After

Notes

• Used react-hot-toast for feedback.
• Stripped quotes from string values.
• Copy button UI matches Bruno’s style using Tailwind utility classes.