chore: release version 2.3.5 and refactor lobby

Bump export_presets.cfg version to 2.3.5. Update CHANGELOG_DRAFT.md.
Refactor lobby.gd into LobbyChat, LobbyMainMenu, LobbyRoomList, LobbyRoom.
Move Nakama config to environment variables in nakama_manager.gd.
Derive auth_manager.gd encryption key from OS.get_unique_id().sha256_text().
Remove Steam email auth fallback. Require auth ticket.
Make GachaManager.pull() async in gacha_panel.gd.
Remove dummy wallet seeding. Add store_type to IAP payload.
Validate IAP receipts server-side in economy.lua.
Register gacha module in main.lua.
Clean backend_service.gd stubs.
Fix featured_banners type safety in gacha_manager.gd. Guards non-array responses.
Move tiles_armagedon_a1.res to assets/models/meshes/. Fix import fallback_path.

addons/gut/one_to_many.gd

@@ -0,0 +1,46 @@
+# ------------------------------------------------------------------------------
+# This datastructure represents a simple one-to-many relationship.  It manages
+# a dictionary of value/array pairs.  It ignores duplicates of both the "one"
+# and the "many".  You can disable ignoring dupliates of the "many" via
+# ignore_many_dupes.  This setting is not retroactive and will only affect
+# new calls to add.
+# ------------------------------------------------------------------------------
+var items = {}
+var ignore_many_dupes = true
+
+# return the size of items or the size of an element in items if "one" was
+# specified.
+func size(one=null):
+	var to_return = 0
+	if(one == null):
+		to_return = items.size()
+	elif(items.has(one)):
+		to_return = items[one].size()
+	return to_return
+
+
+# Add an element to "one" if it does not already exist
+func add(one, many_item):
+	if(items.has(one)):
+		if(!ignore_many_dupes or !items[one].has(many_item)):
+			items[one].append(many_item)
+	else:
+		items[one] = [many_item]
+
+
+func clear():
+	items.clear()
+
+
+func has(one, many_item):
+	var to_return = false
+	if(items.has(one)):
+		to_return = items[one].has(many_item)
+	return to_return
+
+
+func to_s():
+	var to_return = ''
+	for key in items:
+		to_return += str(key, ":  ", items[key], "\n")
+	return to_return