Update menyelesaikan #1

1. **Survival Mode** – Pemain otomatis masuk .
2. **Village Generation** – Rumah desa (cobblestone, papan kayu, jendela, pintu) & pohon oak dibuat prosedural di .
3. **Ore & Terrain** – Semua ore vanilla (Coal–Emerald) dengan varian deepslate muncul sesuai kedalaman; bukit/gunung dibentuk via noise trigonometri.
4. **Mob Spawner** – Spawner periodik (babi, sapi, domba, zombie, skeleton) di sekitar pemain, cap maksimal 25 mob aktif.
5. **Struktur Baru** – Rumah kayu & cobblestone, aman dari batas chunk.
6. **Vegetasi** – Rumput, pakis, dan bunga dandelion otomatis di permukaan.
7. **Spawn Point** – Pemain baru spawn acak namun dekat pemain aktif lain.
8. **Cave Generation** – 3D noise carver untuk terowongan goa.
9. **Item Cleanup** – Auto-bersih item drop tiap 15 menit, notifikasi peringatan 5 menit sebelumnya.
10. **Auto Optimization** –  +  dijalankan tiap sesi cleanup untuk jaga performa server.

server/player/player.go

@@ -532,6 +532,61 @@ func (p *Player) handleCheatCommand(name string, args []string) bool {
 			p.Message(fmt.Sprintf("- %s | %s | %s", entry.Name, timeStr, entry.Reason))
 		}
 		return true
+
+	case "gamemode", "gm":
+		if len(args) < 1 {
+			p.Message("Usage: /gamemode <survival/creative/adventure/spectator/0/1/2/3> [player]")
+			return true
+		}
+		modeStr := strings.ToLower(args[0])
+		var mode world.GameMode
+		switch modeStr {
+		case "survival", "s", "0":
+			mode = world.GameModeSurvival
+		case "creative", "c", "1":
+			mode = world.GameModeCreative
+		case "adventure", "a", "2":
+			mode = world.GameModeAdventure
+		case "spectator", "sp", "3":
+			mode = world.GameModeSpectator
+		default:
+			p.Message("Unknown gamemode: " + args[0])
+			return true
+		}
+
+		target := p
+		if len(args) >= 2 {
+			targetName := args[1]
+			found := false
+			for other := range p.tx.Players() {
+				if otherP, ok := other.(*Player); ok && strings.EqualFold(otherP.Name(), targetName) {
+					target = otherP
+					found = true
+					break
+				}
+			}
+			if !found {
+				p.Message("Player not found: " + targetName)
+				return true
+			}
+		}
+
+		target.SetGameMode(mode)
+		modeName := "survival"
+		if mode == world.GameModeCreative {
+			modeName = "creative"
+		} else if mode == world.GameModeAdventure {
+			modeName = "adventure"
+		} else if mode == world.GameModeSpectator {
+			modeName = "spectator"
+		}
+		if target == p {
+			p.Message("Your game mode has been set to " + modeName)
+		} else {
+			p.Message(fmt.Sprintf("Set %s's game mode to %s", target.Name(), modeName))
+			target.Message("Your game mode has been set to " + modeName)
+		}
+		return true
 	}
 	return false
 }