feat: fix arrow spread pitch issue and prevent mixed left/right clicks
- Fixed side arrow pitch calculation so left/right arrows stay level with the center arrow, even when looking up or down
- Changed side arrow spread to ±20° using yaw-based direction math for consistent spacing
- Added click-side lock system to prevent firing with left click while holding right click and vice versa
- Introduced HOLD_WINDOW_MS (250ms) to define how long the opposite click is blocked
- Cleaned up PlayerInteractEvent logic for easier maintenance
- Preserved original arrow damage, velocity, and sound behavior
- Bump Spigot API to 1.21.8.
- Change base package from me.vermeil to dev.mitra88.
Full Changelog: v1.7.0...1.8.0