chore: Apply modern Go idioms and perform code cleanup

This commit introduces a series of small refactorings and style fixes across the codebase to improve consistency and leverage modern Go features.

Key changes include:
- Adopting the Go 1.22 `reflect.TypeFor` generic function.
- Replacing `interface{}` with the `any` type alias for better readability.
- Using the explicit `http.NoBody` constant for HTTP requests.
- Updating octal literals for file permissions to the `0o` prefix syntax.
- Standardizing comment formatting and fixing minor typos.
- Removing redundant blank lines and organizing imports.

internal/services/parser.go

@@ -61,7 +61,7 @@ func (p *ArticulateParser) FetchCourse(ctx context.Context, uri string) (*models
 
 	apiURL := p.buildAPIURL(shareID)
 
-	req, err := http.NewRequestWithContext(ctx, http.MethodGet, apiURL, nil)
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, apiURL, http.NoBody)
 	if err != nil {
 		return nil, fmt.Errorf("failed to create request: %w", err)
 	}