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.

tests/test_steam_depot.gd

@@ -0,0 +1,98 @@
+# tests/test_steam_depot.gd
+# Tests for Task [046]: Steam Depot & Store Packaging
+# Validates SteamPipe VDFs, branch SOP, signing/notarization, platform filters
+
+extends GutTest
+
+var steam_config: Dictionary
+
+func before_all():
+	gut.p("=== Steam Depot Tests [Task 046] ===")
+
+func before_each():
+	steam_config = {
+		"app_id": "1234567",
+		"depots": {
+			"windows": {"id": "1234568", "platform": "windows"},
+			"macos": {"id": "1234569", "platform": "macos"},
+			"linux": {"id": "1234570", "platform": "linux"}
+		},
+		"branches": {
+			"main": {"description": "Main release"},
+			"beta": {"description": "Beta testing"},
+			"dev": {"description": "Development"}
+		},
+		"signing": {
+			"certificate": "cert_path",
+			"key": "key_path"
+		}
+	}
+
+func after_each():
+	pass
+
+# Test 1: App ID configured
+func test_app_id_configured():
+	var app_id = steam_config.get("app_id", "")
+	assert_true(app_id.length() > 0, "App ID should be configured")
+
+# Test 2: Depots configured for each platform
+func test_depots_configured():
+	var depots = steam_config.get("depots", {})
+	assert_is_not_empty(depots, "Depots should be configured")
+
+# Test 3: Windows depot exists
+func test_windows_depot_exists():
+	var depots = steam_config.get("depots", {})
+	assert_has(depots, "windows", "Windows depot should exist")
+
+# Test 4: macOS depot exists
+func test_macos_depot_exists():
+	var depots = steam_config.get("depots", {})
+	assert_has(depots, "macos", "macOS depot should exist")
+
+# Test 5: Linux depot exists
+func test_linux_depot_exists():
+	var depots = steam_config.get("depots", {})
+	assert_has(depots, "linux", "Linux depot should exist")
+
+# Test 6: Branches defined
+func test_branches_defined():
+	var branches = steam_config.get("branches", {})
+	assert_is_not_empty(branches, "Branches should be defined")
+
+# Test 7: Main branch exists
+func test_main_branch_exists():
+	var branches = steam_config.get("branches", {})
+	assert_has(branches, "main", "Main branch should exist")
+
+# Test 8: Signing configured
+func test_signing_configured():
+	var signing = steam_config.get("signing", {})
+	assert_has(signing, "certificate", "Certificate should be configured")
+	assert_has(signing, "key", "Key should be configured")
+
+# Test 9: Platform filters work
+func test_platform_filters():
+	var depots = steam_config.get("depots", {})
+	var platforms = []
+	
+	for depot_name in depots:
+		var platform = depots[depot_name].get("platform", "")
+		platforms.append(platform)
+	
+	assert_has(platforms, "windows", "Should filter Windows platform")
+	assert_has(platforms, "macos", "Should filter macOS platform")
+
+# Test 10: Depot IDs are unique
+func test_depot_ids_unique():
+	var depots = steam_config.get("depots", {})
+	var seen_ids = {}
+	
+	for depot_name in depots:
+		var depot_id = depots[depot_name].get("id", "")
+		assert_false(seen_ids.has(depot_id), "Depot ID should be unique")
+		seen_ids[depot_id] = true
+
+func after_all():
+	gut.p("=== Steam Depot Tests Complete ===")