Smarter TraceAI and dashboard rhythm

TraceAI teaches more clearly, your dashboard shows weekly study rhythm, and account settings are easier to manage.

• TraceAI prompts were updated for clearer STEM explanations and safer, on-topic answers.
• TraceAI can render formatted content (including equations) more reliably in replies.
• Dashboard adds weekly rhythm and insights so you can see study patterns at a glance.
• Settings modal improvements include session management and clearer security options.
• Confirmation dialogs help prevent accidental deletes on important actions.