Fixes calculations (#2)

Git Level (per commit):
    - Track unique file paths in FilesModified slice
    - FilesChanged = count of unique files in THIS commit

  Aggregator Level (per contributor):
    - Collect all file paths from all commits into a SET
    - FilesChanged = size of the unique file set

  Result:
    - Contributor.FilesChanged = count of UNIQUE files they touched
    - Repository contributor = unique files in THAT repo only

internal/domain/scoring/calculator.go

@@ -293,9 +293,11 @@ func (c *Calculator) checkAchievements(cm *models.ContributorMetrics) []string {
 		case "comment_count":
 			earned = float64(cm.ReviewComments) >= ach.Condition.Threshold
 		case "lines_added":
-			earned = float64(cm.LinesAdded) >= ach.Condition.Threshold
+			// Use meaningful lines to match scoring calculation (excludes comments/whitespace)
+			earned = float64(cm.MeaningfulLinesAdded) >= ach.Condition.Threshold
 		case "lines_deleted":
-			earned = float64(cm.LinesDeleted) >= ach.Condition.Threshold
+			// Use meaningful lines to match scoring calculation (excludes comments/whitespace)
+			earned = float64(cm.MeaningfulLinesDeleted) >= ach.Condition.Threshold
 		case "avg_review_time_hours":
 			// For avg review time, lower is better, so lower threshold = harder achievement
 			if cm.AvgReviewTime > 0 && cm.AvgReviewTime <= ach.Condition.Threshold {

internal/domain/scoring/calculator_test.go

@@ -452,6 +452,8 @@ func TestCalculator_AllAchievementTypes(t *testing.T) {
 						ReviewComments:          25,
 						LinesAdded:              1500,
 						LinesDeleted:            600,
+						MeaningfulLinesAdded:    1500,
+						MeaningfulLinesDeleted:  600,
 						AvgReviewTime:           1.5,
 						UniqueReviewees:         7,
 						RepositoriesContributed: []string{"owner/repo1", "owner/repo2"},