[NaySurGithub]

Batch 4 of the plugin API additions.

Depends on the batch 3 PR (#15); merge that one first. The base branch is the batch 3 branch so the diff only shows this batch.

What it adds

• Text kept per plugin on entities and players (entityData, entitySetData, entityDataCount/Key) and on items (itemData, itemSetData, itemDataCount/Key), saved with them. Keys belong to the calling plugin.
• NBT: itemNbt/itemSetNbt read and replace an item's tag as little-endian NBT; entityNbt returns what the server would save for an entity (read only).
• C++ (Entity, Item), Java (plugin.data(), Item.nbt(), Entity.nbt()) and Wasm bindings, README section.

All functions are appended at the end of FalconServerApi (API 1.0.6, bumped by batch 1).

Not added

• Entity NBT write: loading a whole actor tag back into a live entity resets it and is not something the server does outside its own load path; only reading is offered.

Checks

CI of the batch 6 branch (feat/world), which contains this one: Linux, Windows (MSVC and MinGW), .NET and Java jobs green; the macOS jobs were cancelled by the runner, as on main.