perf: Optimize memory allocations and string operations

[watany-dev]

• Use strings.Builder instead of += concatenation in benchmark test
• Pre-allocate slices with known capacity in ParsePathFile,
  extractJobOrderFromNode, and DiscoverWorkflows
• Use strings.EqualFold for case-insensitive comparison instead of
  strings.ToLower to avoid unnecessary string allocations

These changes reduce memory allocations and improve performance by:

• Avoiding O(n²) string concatenation in loops
• Reducing slice reallocations during append operations
• Eliminating temporary string allocations for case comparison