Endermen and pyramid attraction

• Added Enderman kill rewards and banners, including /mobbanner give enderman.
• A standing banner centered on a solid 5x5 / 3x3 / 1x1 pyramid of iron, gold, emerald, diamond, or netherite blocks now attracts its mob instead of suppressing it. Mixed materials are allowed.
• Each eligible spawn gets one extra nearby spawn attempt (2x attempts, not guaranteed 2x population). Duplicate attractors do not stack; a normal banner of the same type overrides attraction and suppresses spawning.
• Extra attempts check space, ground/water, light, world border, living-entity collisions, and distance from players. They use CUSTOM spawn reason and cannot recursively trigger boosts. They do not rerun the full vanilla biome/structure/mob-cap rules.
• Existing banners and kill progress remain compatible. Remove the old JAR before installing this version.
• Verified with 65 passing tests; live Paper 26.3 smoke testing is recommended.