Phase 7: netfox + godot-jolt stack upgrade

Stack installed:
- netfox v1.35.3 (core + extras + noray + internals)
- godot-jolt v0.16.0-stable

Architecture:
- Server: ENet transport (works headless, no netfox deps)
- Client/Editor: netfox rollback (RollbackSynchronizer, TickInterpolator)

New/modified:
- docs/migration-netfox-plan.md — migration architecture
- scripts/network/network_manager.gd — netfox-aware ENet fallback
- scripts/network/player.gd — clean base player
- client/characters/player_netfox.gd — rollback player w/ WeaponManager
- client/characters/input/player_net_input.gd — BaseNetInput subclass
- client/characters/character/fps_character_controller.gd — netfox input feed
- client/weapons/ — weapon data, registry, TacticalWeaponHitscan, WeaponManager
- client/scripts/round_replicator.gd — client-side round state bridge
- server/scripts/round_manager.gd — improved state machine
- server/scripts/plugin_api/plugin_manager.gd — refined plugin system
- config: enemy_tag, ally_tag for meatball targeting

Removed: old C++ SimulationServer GDExtension (replaced by netfox rollback)

client/weapons/scripts/tactical_weapon_hitscan.gd

@@ -0,0 +1,89 @@
+## TacticalWeaponHitscan — rollback-aware hitscan weapon for the tactical shooter.
+##
+## Extends NetworkWeaponHitscan3D with per-limb damage, team checks,
+## and headshot detection.
+##
+## This script is ONLY loaded from client scenes where netfox is active.
+## The server handles damage authority directly.
+
+extends "res://addons/netfox.extras/weapon/network-weapon-hitscan-3d.gd"
+class_name TacticalWeaponHitscan
+
+## Weapon data resource (stats) — set on spawn
+var weapon_data: WeaponData = null
+
+## Weapon owner's peer ID — set on spawn
+var owner_peer_id: int = -1
+
+## Cooldown tick for rate-of-fire limiting
+var _last_fire_tick: int = -1
+
+func _can_fire() -> bool:
+	if weapon_data == null:
+		return false
+	if weapon_data.fire_mode == WeaponData.FireMode.MELEE:
+		return true  # Melee always "can fire"
+	
+	# Rate-of-fire check using network tick
+	var nt = Engine.get_singleton(&"NetworkTime")
+	if nt == null:
+		return true
+	var current_tick := nt.tick if nt.has_method(&"get_tick") else 0
+	if _last_fire_tick >= 0:
+		var tick_interval := maxi(1, int(weapon_data.fire_rate / 64.0))
+		if current_tick - _last_fire_tick < tick_interval:
+			return false
+	return true
+
+func _can_peer_use(peer_id: int) -> bool:
+	return peer_id == owner_peer_id
+
+func _after_fire():
+	# Track fire tick for cooldown
+	var nt = Engine.get_singleton(&"NetworkTime")
+	if nt != null:
+		_last_fire_tick = nt.tick if nt.has_method(&"get_tick") else 0
+
+## Handle a raycast hit — called on ALL peers with rollback reconciliation.
+func _on_hit(result: Dictionary):
+	if weapon_data == null:
+		return
+	if not multiplayer.is_server() and not is_multiplayer_authority():
+		return  # Only server/authority applies damage
+
+	var collider := result.get("collider")
+	if collider == null:
+		return
+
+	# Determine limb hit via collision groups
+	var damage_multiplier: float = weapon_data.chest_multiplier
+	var is_headshot := false
+
+	if collider is Node:
+		if collider.is_in_group(&"head"):
+			damage_multiplier = weapon_data.headshot_multiplier
+			is_headshot = true
+		elif collider.is_in_group(&"chest"):
+			damage_multiplier = weapon_data.chest_multiplier
+		elif collider.is_in_group(&"waist"):
+			damage_multiplier = weapon_data.waist_multiplier
+		elif collider.is_in_group(&"legs"):
+			damage_multiplier = weapon_data.leg_multiplier
+
+	var final_damage := int(weapon_data.damage * damage_multiplier)
+
+	# Find the player node from the collider
+	var player := _find_player(collider)
+	if player != null and player.has_method(&"apply_damage"):
+		if is_headshot:
+			print("[TacticalWeapon] HEADSHOT on %s for %d" % [player.name, final_damage])
+		player.apply_damage(final_damage, owner_peer_id, weapon_data.weapon_id)
+
+## Find a player node walking up the scene tree.
+func _find_player(node: Node) -> Node:
+	var current = node
+	while current != null:
+		if current.has_method(&"apply_damage") or current.is_in_group(&"players"):
+			return current
+		current = current.get_parent()
+	return null