Crafting UI overhaul, hotbar, item icons, signal + path bug fixes

• Add progress bar + ‘Crafting: X’ label to crafting panel
• Add crafting_started/updated/finished signals to ComponentCrafter
• Rebuild recipe buttons with icon + inputs->outputs layout
• Add ITEM_COLORS map for item color fallbacks
• Move hotbar from factory HUD to player CanvasLayer (8 slots)
• Player._refresh_hotbar() renders slots with amount labels
• interaction_ui routes all inventory refreshes to the player
• Rewrite toggle_inventory() for player-owned hotbar
• Remove InventoryPanel/InventoryList from factory.tscn
• Add 9 hand-drawn item icons in assets/icons/
• Enable GDDraw plugin
• Fix duplicate crafting_finished emit in _finish_craft
• Fix crafting_finished.emit({},[]) -> emit([]) arg count
• Guard all signal connects with is_connected()
• Fix ‘ProgresssBar’ typo in _find_crafting_nodes
• Fix broken ‘rect.texture = tex.rect.expand_mode’ line
• Fix ‘unobtainium’ -> ‘unobtanium’ item id typo
• Fix vector2 -> Vector2 (lowercase)