Renewable resources: tree growth + WildGrowth + Quarry on BigRockNode

Trees: 4 growth stages (Sapling→Young→Growing→Mature), only Mature
yields wood. WildGrowth ticker fires every in-game hour; rejection-
samples grass tiles and plants a sapling with ~30% probability (capped
at MAP_TREE_LIMIT=60). New `paint_plant_tree` designation lets the
player manually plant — ghost sapling registered as a build_site that
ConstructionProvider fulfils. Stage round-trips through save/load.
Initial seed mixes 4 saplings + 6 mature so growth is visible day 1.

Quarry: new BigRockNode entity (2×2 permanent stone outcrop, never
depletes). 3 nodes seeded far from cabin. New QuarryWorkbench
(extends Workbench, auto-FOREVER `quarry_stone` bill, recipe drops
1 stone per 300 work-ticks). New `paint_quarry` designation only
accepts BigRockNode tiles. CraftingProvider now supports recipes
with `ingredient_count == 0` — skips ingredient-fetch and goes
straight to walk+craft toils. Recipe gains `ingredient_count` field
(defaults 0). Save/load layering: big_rock_node spawns at priority 0
(same as rock/tree), quarry_workbench at priority 2 (after the node).

UI: Plant tree + Build quarry buttons added to Build drawer.
build_drawer_thumb gains `plant_tree` (sapling sprout in dirt) and
`paint_quarry` (stone block + chisel + cut-stone pile) shapes.
inspect_tooltip recognises BigRockNode + shows tree growth stage on
hover.

Delegation: gdscript-refactor (Sonnet ×2) for trees full impl +
quarry skeleton; quick-edit (Haiku) for CraftingProvider no-ingredient
plumbing + TopBar polish; integration handled on Opus.

autoload/world.gd

@@ -19,6 +19,7 @@ var work_providers: Array = []
 # from their _ready/_exit_tree. Phase 16 will add stable IDs and persistence wiring.
 var trees: Array = []          # Array of Tree
 var rocks: Array = []          # Array of Rock
+var big_rock_nodes: Array = [] # Array of BigRockNode (permanent stone outcrops)
 var items: Array = []          # Array of Item (on-floor stacks)
 var stockpiles: Array = []     # Array of StorageDestination (StockpileZone for now; containers Phase 5)
 
@@ -207,6 +208,24 @@ func unregister_rock(r) -> void:
 	rocks.erase(r)
 
 
+func register_big_rock_node(n) -> void:
+	if not big_rock_nodes.has(n):
+		big_rock_nodes.append(n)
+
+
+func unregister_big_rock_node(n) -> void:
+	big_rock_nodes.erase(n)
+
+
+## Returns the BigRockNode whose 2×2 footprint covers `tile`, or null.
+## Used by `paint_quarry` designation to validate the build site.
+func big_rock_node_at_tile(tile: Vector2i):
+	for n in big_rock_nodes:
+		if n.is_at(tile):
+			return n
+	return null
+
+
 func register_item(it) -> void:
 	if items.has(it):
 		return