adding Target CPA and SGPA calculator

[tashifkhan]

This pull request introduces a CGPA target calculator feature to the grades view and adds new utility functions for consistent decimal formatting. The main changes include integrating the CGPATargetCalculator component, updating imports, and providing helper functions for decimal precision in the utils.js file.

Feature Addition

• Added the CGPATargetCalculator component to the grades view, allowing users to calculate target CGPA directly from the UI. The component receives w, semesterData, and a guest flag (based on MockWebPortal) as props. (jportal/src/components/Grades.jsx) [1] [2] [3]

UI and Import Updates

• Updated imports in Grades.jsx to include CalculatorIcon and CGPATargetCalculator for the new calculator feature. (jportal/src/components/Grades.jsx)

Utility Functions

• Added new utility functions in utils.js for consistent decimal formatting: getDecimalPlaces, formatDecimal, getAttendanceDecimal, getGpaDecimal, and getTargetGpaDecimal, all defaulting to 2 decimal places. (jportal/src/lib/utils.js)

Issues

• add cgpa goal just like attendance goal #30

[tashifkhan]