feat: implement advanced credit scoring with on-chain history

[ikemHood]

Description

Implemented an advanced credit scoring system within the TeachLinkBridge contract. This feature allows tracking of user creditworthiness based on their on-chain activity, specifically course completions and community contributions.

Changes

• New Module: Added score.rs to handle credit scoring logic.
• Data Structures: Introduced ContributionType (Content, Code, Community, Governance) and Contribution structs.
• Storage: Added persistent storage for user credit scores, completed courses history, and contribution records.
• Events: Added CreditScoreUpdated, CourseCompleted, and ContributionRecorded events.
• API: Exposed record_course_completion, record_contribution, and getters for score/history in the public interface.
• Access Control: Restricted recording functions to admin actions.

Verification

• Added a new test suite tests/test_score.rs covering the full scoring flow.
• Verified:
  • Initial score is 0.
  • Course completion increases score.
  • Duplicate course completion does not double-count.
  • Contributions increase score.
  • Data persistence and retrieval.
• Ran usage regression tests on existing modules.

Checklist

• Code compiles
• New tests pass
• No regressions in existing tests

Closes #58

[ISTIFANUS-N]

@ikemHood resolve conflicts

[ISTIFANUS-N]

@ikemHood please you still have conflicting files.

[ikemHood]

@ISTIFANUS-N Done