Add freemium access economy and token store

scripts/ui/main.gd

@@ -350,6 +350,11 @@ func _build_ui() -> void:
 	donations.main = self
 	screens_container.add_child(donations)
 	screens["donations"] = donations
+	var access_store := preload("res://scripts/ui/access_store_screen.gd").new()
+	access_store.name = "AccessStoreScreen"
+	access_store.main = self
+	screens_container.add_child(access_store)
+	screens["access_store"] = access_store
 
 	feedback_dialog = preload("res://scripts/ui/app_feedback_dialog.gd").new()
 	feedback_dialog.name = "AppFeedbackDialog"
@@ -369,10 +374,16 @@ func _build_ui() -> void:
 
 	AuthState.auth_changed.connect(_on_auth_changed)
 	AuthState.session_expired.connect(_on_session_expired)
+	QuestionBankService.access_required.connect(_on_qbank_access_required)
 	_refresh_header_controls()
 	_build_app_menu()
 
 
+func _on_qbank_access_required(_message: String) -> void:
+	if AuthState.is_logged_in:
+		show_screen("access_store")
+
+
 func _build_sidebar() -> PanelContainer:
 	var panel := PanelContainer.new()
 	panel.name = "Sidebar"
@@ -426,6 +437,7 @@ func _populate_navigation(container: VBoxContainer, include_brand: bool) -> void
 	spacer.size_flags_vertical = Control.SIZE_EXPAND_FILL
 	container.add_child(spacer)
 	container.add_child(HSeparator.new())
+	_add_nav_button(container, "access_store", "Credits & Access", "clock-3", true)
 	_add_nav_button(container, "donations", "Support RanaZe", "heart-pulse", true)
 	_add_nav_button(container, "performance", "Profile", "user-round", true)
 	_add_nav_button(container, "settings", "Settings", "settings", true)
@@ -471,6 +483,7 @@ func _on_navigation_pressed(key: String) -> void:
 		"notes": show_screen("notes")
 		"bookmarks": show_screen("bookmarks")
 		"donations": show_screen("donations")
+		"access_store": show_screen("access_store")
 		"logout": _logout()
 
 
@@ -489,7 +502,8 @@ func _update_header_title(screen_name: String) -> void:
 		"settings": "Settings",
 		"notes": "Notes",
 		"bookmarks": "Bookmarks",
-		"donations": "Support RanaZe"
+		"donations": "Support RanaZe",
+		"access_store": "Credits & Access"
 	}
 	header_title.text = str(titles.get(screen_name, ""))
 
@@ -814,6 +828,9 @@ func _on_theme_changed(is_dark_mode: bool) -> void:
 	var donations = screens.get("donations")
 	if donations != null and donations.has_method("refresh_theme_controls"):
 		donations.refresh_theme_controls()
+	var access_store = screens.get("access_store")
+	if access_store != null and access_store.has_method("refresh_theme_controls"):
+		access_store.refresh_theme_controls()
 	var player = screens.get("player")
 	if player != null and player.has_method("refresh_theme_controls"):
 		player.refresh_theme_controls()