feat(teacher-dashboard): Teacher Assessment Dashboard, Visual Progress Tracker & Onboarding Doc

[jiyasingh951s-arch]

Summary of Changes

• Teacher Diagnostic & Progress Tracker (TeacherDashboard.tsx): Added responsive visual analytics for teachers to monitor student baseline performance, competency distributions, and attendance-score correlations.
• Student Analytics Hook (useStudentAnalytics.ts): Implemented client-side aggregation logic grouping students into FLN performance tiers (Needs Intervention, Progressing, Proficient).
• Targeted Remediation Queue: Added an actionable table to directly identify struggling students below baseline thresholds for targeted worksheet generation.
• Onboarding Documentation: Added Ideas/ONBOARDING-Jiya-Singh.md covering system audit, architecture gaps, feature proposals, and contribution details.

💡 How This Contribution Differs from Existing PRs

• Dedicated Class-Level Visual Analytics (vs. PR feat(teacher-workflow): add multi-class student management, diagnostics, performance dashboard and evaluation reports #74 & PR feat: Upgrade Regional Performance Analytics Dashboard with Multi-Parameter Filtering #163): Focuses specifically on frontline classroom diagnostic charts and attendance-score correlation rather than admin oversight or raw roster CRUD.
• Aggregate Class Mastery Breakdown (vs. PR feat: add interactive student progress tracking panel component #49): Provides high-level cohort distribution rather than single-student profile cards.
• Actionable Remediation Pipeline (vs. PR feat: add automated intervention priority classification and dashboard #54 & PR feat: Add Intervention Dashboard #59): Directly connects low-score benchmarks (<50%) to instant worksheet assignment triggers for teachers.
• Self-Contained Client State: Includes resilient fallback data in useStudentAnalytics.ts ensuring clean client-side rendering.

Visual Preview

Testing & Verification

• Tested dynamic grade (All, 1, 2, 3) and competency level (10, 16, 25, 31) filtering.
• Verified Recharts responsive bar and scatter chart layouts.
• Confirmed fallback handling for mock datasets.