feat(progression): XP, niveaux et popups flottants (+N XP)

Nouvel autoload PlayerProgress qui gagne de l'XP sur:
- cassage de blocs (gain variable selon le type: perle, épave, coral > sand)
- collecte de perles (+25)
- crafting (+10)
- paliers de profondeur atteints (+20 à 10/25/50/75/100m)

HUD: barre XP + label niveau en bas centre, bannière "NIVEAU X" au level-up
(son bulle + fade). Popup 3D "+N XP" spawn au point d'action.

Boucle court-terme dopamine: chaque action = feedback visuel immédiat.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scripts/inventory/CraftingRecipes.gd

@@ -52,4 +52,12 @@ static func craft(inventory: Inventory, recipe_index: int) -> bool:
 	var leftover: int = inventory.add_item(recipe["output"]["item_id"], recipe["output"]["count"])
 	if leftover > 0:
 		push_warning("CraftingRecipes: craft overflow — %d items lost" % leftover)
+	_award_craft_xp(recipe)
 	return true
+
+
+static func _award_craft_xp(recipe: Dictionary) -> void:
+	var pp: Node = Engine.get_main_loop().root.get_node_or_null("/root/PlayerProgress")
+	if pp == null:
+		return
+	pp.award(pp.XP_CRAFT, "craft %s" % str(recipe.get("name", "")), Vector3.ZERO)