[Frontend] Add quick runway preset buttons (+7 days, +30 days, +90 days) to TopUpModal #1635

Overview

When topping up an active stream in frontend/src/components/stream-creation/TopUpModal.tsx, senders must manually calculate how many tokens are needed to extend the stream by a specific number of days.

Problem

• Calculating ratePerSecond * 86400 * days mentally is error-prone and slows down recurring payroll top-ups.

Proposed Changes

1. Add three quick-fill pill buttons inside TopUpModal.tsx: +7 Days, +30 Days, and +90 Days.
2. Clicking a preset automatically computes the token amount from the stream's ratePerSecond and populates the amount input field.

Acceptance Criteria

• Clicking +7 Days, +30 Days, or +90 Days populates the exact deposit amount required.
• Displays the new projected end date below the input when an amount is entered.
• Unit test added in frontend/src/components/stream-creation/__tests__/TopUpModal.test.tsx.