feat: implement dynamic category icon mapping and unit tests

[yunus-dev-codecrafter]

closes #177

Title: Refine and implement: Incorrect category icon mapping

Description

This PR addresses the incorrect category icon mapping identified during the audit (Internal Ref #FE-177). It replaces hardcoded icons with a centralized, dynamic mapping system that supports various claim categories and includes a robust fallback mechanism.

Changes

• Centralized Mapping Utility: Created category-icons.tsx to manage the association between categories and Lucide icons.
• Dynamic Icon Retrieval: Implemented getCategoryIcon with normalization logic (case-insensitive, trimming) to ensure reliable matching.
• UI Integration:
  • Updated ActiveClaimsTable.tsx to display category-specific icons in the main feed.
  • Updated ClaimStats.tsx to replace generic icons with specific ones in the claim detail view.
• Unit Testing: Added category-icons.test.tsx to verify mapping accuracy, normalization, and fallback behavior.

Mapped Categories

Category	Icon
Climate	Cloud
Health	Activity
Technology	Cpu
Misinformation	AlertCircle
Fraud	AlertTriangle
Politics	Globe
Others (Fallback)	FileText

Verification & Testing

• Unit Tests: All tests passed, covering exact matches, case variations, and empty inputs.
• UI/UX: Verified that icons render correctly across different components without regressions.
• Integrity: Ensured no impact on the underlying data structures or protocol invariants.