Neroland Core

Additive public-API release for cross-mod material discovery.

Added

• Typed per-material milestone definitions under data/<namespace>/neroland_material_milestones/*.json, with player/team/server scopes.
• Server-authoritative MaterialMilestones observation/query API, validated observation kinds, change events, client sync, direct player export, and shared PlayerDataErasure integration.
• Canonical nerolandcore:material_discovered definition for owner-mod, planet-visit, legitimate player-pickup, and administrator observations.
• Downstream registration attachment and configured-stack contributions to the shared Neroland creative tab, allowing component-backed variants without per-variant registry ids.

Changed

• Formalised NF (Nero Flux) as the player-facing power name. Existing energy Java types, capability ids, persisted values, config keys, and FE conversion semantics are unchanged.