fix/terraria 1.4.5.7 port

[bulkinglb]

Stacked on #282 (@hufang360) — that PR gets 1.4.5.7 building, this makes NPCs actually spawn. Reduces to one commit once #282 merges.

Bug (from #281): server boots and clients connect, but no enemies ever spawn. Town NPCs are fine.

Cause: OTAPI 3.3.12 changed Hooks.NPC.InvokeCreate to take the slot and generation, so the hook is now responsible for placing the NPC in Main.npc. 3.3.11 did that inside NewNPC (Main.npc[index] = nPC; nPC.whoAmI = index; nPC.ResetForNewNPC();). 3.3.12 dropped those lines but its fallback still returns a bare new NPC(). Nothing subscribes to Hooks.NPC.Create, so every spawn applied SetDefaults/active/timeLeft to a detached instance that was never stored Main.npc[slot] stayed empty and GetAvailableNPCSlot handed back the same slot forever.

Fix: subscribe to Hooks.NPC.Create and use the engine's own factory NPC.NewNPCInstanceInSlot(slot, generation) — it stores the instance, sets whoAmI, bumps the generation clients use for recycled slots, and clears stale cross-references via ResetNPCSlotData. OTAPI should arguably fix its fallback too; this makes TSAPI correct either way. Tested: .NET 9, linux-arm64, vanilla 1.4.5.7 client. Before: zero non-town NPCs, NewNPC called repeatedly always returning the same slot. After: enemies spawn, despawn and sync normally.

Thanks @hufang360 for #282, @ZakFahey for the TShock-side port in Pryaxis/TShock#3299, and @bryldd for digging into the PR before.

[SignatureBeef]

this can be removed - otapi 3.3.13 fixes this internally.

[hufang360]

Hi @SignatureBeef,

I'm the author of #282, which overlaps heavily with this PR. I'd like to fold my changes into #283 so we don't keep two parallel 1.4.5.7 ports open.

What I've verified so far with OTAPI.Upcoming 3.3.13 (the fix for the NPC spawning issue):

• TSAPI builds clean on net9 with 3.3.13.
• The full TShock stack boots against the vanilla 1.4.5.7 server: Protocol v1.4.5.7 (325), world generation and listen OK.

Since 3.3.13 fixes the NPC create path internally, the OnCreate workaround in NpcHooks.cs can be dropped once we bump — consistent with your earlier comment.

How would you prefer to proceed?

1. Keep fix/terraria 1.4.5.7 port #283 as the base, bump OTAPI to 3.3.13 and remove the OnCreate fallback — I'm happy to push those changes to this branch or provide a patch;
2. Or close both and consolidate into one clean PR.

I'll close #282 either way. Happy to help with whatever shape you prefer.

[bulkinglb]

@hufang360 option 1 works for me, and it's done — #283 is now your commit plus a one-line bump to 3.3.13, with the OnCreate workaround removed per @SignatureBeef's review. NpcHooks.cs is untouched from your version again.

Thanks for verifying 3.3.13.

TShock side is Pryaxis/TShock#3301, also bumped to 3.3.13.