Enhance stats and telemetry features with formatting updates

[kbtale]

Summary

Implements a privacy-first local analytics and statistics dashboard across all 24 interactive tools in Useless Polymath. Tracks practice telemetry (attempts, correct answers, accuracy rate, streaks, high scores, activity timestamps), computes multi-domain subject mastery (Novice, Apprentice, Proficient, Master), displays a 30-day practice activity heatmap, unlocks 8 milestone achievements with real-time celebratory in-app toast notifications, and provides full JSON backup export and import data portability.

Key Additions and Changes:
Storage and Telemetry Engine (src/services/storage.ts): Granular per-module telemetry tracking stored locally under polymath_stats_* keys with automatic backward-compatibility migration from legacy streak and high score keys. Full JSON backup export and validated import with error resilience.
Achievements and Mastery Logic (src/modules/stats/logic.ts): Pure domain logic computing subject mastery across 5 categories (Chronometry, Cryptography, Logic, Networks, Science & Electronics), 30-day activity heatmap intensity levels, and 8 milestone achievement evaluations.
Practice Coordinator and Toast Alerts (src/hooks/usePracticeStreak.ts, src/components/core/AchievementToast.tsx): Seamless telemetry auto-logging on practice submissions that dispatches real-time celebratory in-app toast banners when milestone achievements are unlocked.
Full-Screen Stats Dashboard (src/components/stats/StatsDashboard.tsx): Dedicated analytics dashboard with overview KPI cards, 30-day heatmap grid, domain mastery progress meters, milestone achievements showcase, sortable/filterable per-module telemetry table, and backup data management controls.
Navigation and Deep-Linking (src/components/layout/AppShell.tsx, src/hooks/useModuleNavigation.ts): Direct access via top header "Stats" button, sidebar navigation, and #stats URL hash deep-linking.
100% Locale Parity: Complete translations across English (en), Spanish (es), and Italian (it) verified by automated parity tests.

Type of Change

• Bug fix
• New feature
• Refactoring
• Performance improvement
• Accessibility improvement
• Documentation update

Checklist

• npm run check passes (Biome lint & format)
• npm run test passes (all unit tests)
• npm run build passes (TypeScript strict mode)
• New i18n keys added to all 3 locales (en, es, it)
• No inline styles added (use SCSS modules)