M2.2: player bodies, name tags, shared island and checked movement

- Joining loads the server's island (seed, spawn, clock); the server
  generates the same terrain from its seed and keeps a world clock that
  pauses when empty
- Other players are procedural low-poly characters in their chosen colours
  with name tags (hidden by walls, fading with distance), walk/run/swim
  animation and held items
- Movement: local and instant, sent at 20 Hz stamped with the sender's
  clock; the server refuses impossible moves (speed, rising, leaving the
  island, underground) and sends the player back; flagged respawns allowed
- Avatars drawn 100 ms behind and interpolated, with brief extrapolation
- Online: no pausing, player list in the Esc menu, Disconnect back to the
  title (with the reason); animals off and world changes local-only until
  M2.3-M2.5, shown on the HUD
- test_net_world: real server + walking and cheating bots at 100 ms +/-
  30 ms simulated latency (27 checks)

tests/net_bot.gd

@@ -9,6 +9,69 @@ extends SceneTree
 
 var _outcome := ""
 var _reason := ""
+var _pos := Vector3.ZERO
+var _corrections := 0
+var _others := {}            ## name -> last position seen in a snapshot
+var _terrain: Node3D
+
+## Walks (and optionally cheats) on the server's island, sending positions
+## 20 times a second like a real client. Corrections from the server are
+## obeyed, as the real client does.
+##   --walk line --speed 4 --walk-time 3   walk along +X, then stand still
+##   --cheat teleport   after 1 s, claim to be 60 m away
+##   --cheat outside    walk straight out toward the world's edge at 7 m/s
+##   --cheat respawn    a flagged teleport to the spawn (legitimate)
+func _move(net: Node, args: Dictionary, res: Dictionary) -> void:
+	_terrain = load("res://scripts/world/terrain.gd").new()
+	root.add_child(_terrain)   # takes its seed from the server (net.world_info)
+	_pos = net.world_info.get("spawn", Vector3.ZERO)
+	net.corrected.connect(func(p): _corrections += 1; _pos = p)
+	net.snapshot.connect(func(_t, states):
+		for s in states:
+			if net.players.has(int(s[0])):
+				_others[net.players[int(s[0])].name] = s[1])
+	var mode := String(args.get("walk", args.get("cheat", "")))
+	var speed := float(args.get("speed", 4.0))
+	var dur := float(args.get("walk-time", 3.0))
+	res.walk_start = [_pos.x, _pos.y, _pos.z]
+	var t := 0.0
+	var dir := Vector3(1, 0, 0)
+	if mode == "outside":
+		dir = Vector3(_pos.x, 0, _pos.z).normalized() if Vector2(_pos.x, _pos.z).length() > 1.0 else Vector3(1, 0, 0)
+		speed = 7.0
+		dur = 40.0
+	var step := 0.05
+	var prev_us := Time.get_ticks_usec()
+	while t < dur and net.state == "connected":
+		var now_us := Time.get_ticks_usec()
+		var real_dt := (now_us - prev_us) / 1000000.0
+		prev_us = now_us
+		var teleported := false
+		var anim := 1
+		match mode:
+			"teleport":
+				if absf(t - 1.0) < step * 0.5:
+					_pos += Vector3(60, 0, 0)
+				anim = 0
+			"respawn":
+				if absf(t - 1.0) < step * 0.5:
+					var sp: Vector3 = net.world_info.get("island_spawn", _pos)
+					_pos = sp + Vector3(0.5, 0, 0.5)
+					teleported = true
+				anim = 0
+			_:
+				_pos += dir * speed * real_dt   # real elapsed time, like the game's physics
+		_pos.y = _terrain.sample_height(_pos.x, _pos.z)
+		net.send_state(_pos, 0.0, 0.0, anim, "", teleported)
+		await create_timer(step).timeout
+		t += step
+		if mode == "outside" and _corrections > 0 and t > 1.0:
+			break
+	res.walk_end = [_pos.x, _pos.y, _pos.z]
+	# Stand still for a moment, still sending, so the last position settles.
+	for _i in range(10):
+		net.send_state(_pos, 0.0, 0.0, 0, "", false)
+		await create_timer(step).timeout
 
 func _initialize() -> void:
 	_run.call_deferred()
@@ -35,6 +98,8 @@ func _run() -> void:
 		res.joined = true
 		res.server_name = net.server_info.get("server_name", "")
 		res.admin = bool(net.players.get(net.local_peer, {}).get("admin", false))
+		if args.has("walk") or args.has("cheat"):
+			await _move(net, args, res)
 		var saw := {}
 		var stay := float(args.get("stay", 2.0))
 		var s := 0.0
@@ -44,6 +109,11 @@ func _run() -> void:
 			await create_timer(0.1).timeout
 			s += 0.1
 		res.saw = saw.keys()
+		res.corrections = _corrections
+		res.final_pos = [_pos.x, _pos.y, _pos.z]
+		if _others.has("Alice"):
+			var ap: Vector3 = _others.Alice
+			res.alice_pos = [ap.x, ap.y, ap.z]
 		net.leave()
 		for _i in range(10):
 			await process_frame