feat(block): make furnaces smelt, burn fuel and show progress - #156

Description

Furnaces were a block and a recipe that produced a block nobody could use: no screen, no smelting, no fuel, no cook time.

• A smelting table and a fuel table in item: ores and raw metals into ingots, food into cooked food, sand into glass, and the usual fuels from a stick to a lava bucket.
• Right clicking a furnace, blast furnace or smoker opens its own screen with the three slots the client expects. Contents go through the same per-position container storage the chest already uses, so they persist and drop on break like anything else.
• A furnace burns a piece of fuel only when there is something to cook and somewhere to put it, cooks one item per burn cycle, and swaps between its lit and unlit block while keeping the way it faces. Blast furnaces and smokers cook in half the time.
• Progress is sent to whoever has the furnace open, so the flame and the arrow move.
• Ticking arrives through a new worldrt.BlockEntityTicker, the same shape as the existing PlayerTicker: the world runtime owns the clock, the session decides what a tick means. Only furnaces with something to do are visited.

Related issue

Part of #125

Two gaps worth naming:

• Burn and cook progress is in memory. A furnace goes out across a restart instead of resuming mid-cook; its contents are persisted either way. Persisting it means widening the world's tile data, which is a change of its own.
• Taking the output does not award experience yet. That waits on the experience system in Experience: levels, orbs and costs #139 (PR feat(player): add experience levels, orbs and the xp command #151); the smelting table already carries the per-recipe amount for when it lands.

ContainerSetDataPacket has no alias in protocol.current, so the progress packet is reached through the version it was last changed in - the same workaround as MobArmorEquipmentPacket in #149. Both would be better as aliases upstream.

Checklist

• v -check . is clean
• v test server/item/smelting_test.v, server/block/furnace_test.v, server/world/db, and the session inventory/items/blocks/runtime/registry/place/break tests are green
• Follows the conventions in AGENTS.md (OOP, pub/capitalized exports, no import cycles, minimal comments)
• Cross-session gameplay state is only mutated on its owning world's actor thread (via world_call/wr.submit/WorldTx), never through a global Hub actor
• No unrelated changes bundled in