Grade Calc Instructions

Instructions have been written for Grade Calc, and need to be added to the page. There should be an info bubble in the top corner that they can click to see the instructions, but they should also pop up automatically every time a user navigates to Grade Calc. Add a checkbox for "Don't show me this again" if they don't want it to pop up every time.

No files or tests are named. Start by locating the Grade Calc page/component and its route in the JavaScript frontend, then inspect existing popup/tooltip and preference-storage patterns in nearby code. Check where visit-level flags are persisted so the auto popup can be suppressed after “Don't show me this again.” Done means the instructions are accessible from a top-corner info bubble, auto-open on Grade Calc load, and stop showing after the checkbox is selected.

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