feat: Enhance Test UI and User Experience

[zihanKuang]

Design & Refactoring

• UI Consistency: Create a single layout for "Ready," "Locked," and "Results" pages. They should look identical, with variations only in status info and action buttons.

Page-Specific Tasks

• Locked Page: Remove negative design. Reuse the standard layout. Gray out the "Start Test" button and list all prerequisites, showing both completed (✓) and uncompleted (✗) items.
• Results Page: Reuse the standard layout.
  • Change the title.
  • Delete the "Please answer the following questions" text.
  • Use "Test" over "Exam" and "Taken on" over "Submitted."
  • Focus the layout on the last attempt, showing the date, score vs. passing score, and correct/incorrect stats.
  • Move buttons to the bottom and rename them to "Review Last Test Results" and "Retake Test."
• In-Progress Page: Add a fixed display of "Attempts: X / Y" and "Passing Score: 70%."

Component & Style Unification

• Buttons: Apply standard CSS from the sistent.
• Icons: Replace all Bootstrap icons with standard icons from the sistent.
• Fonts: Standardize font sizes to at least 0.9rem, with key info using larger sizes.

[Namanv0509]

I will make sure to use Sistine and improve the ux of the page.