Motivation

• Ensure dashboard widgets only list and run against plugin engines that are enabled in application settings.
• Prevent widgets (notably the pinned-query widget) from executing searches against disabled or missing plugins.
• Provide clear UX feedback when a configured engine is disabled or unavailable and fall back to a valid engine where sensible.

Description

• Add enabled_plugins: Option<&HashSet<String>> to WidgetSettingsContext and DashboardContext so widgets can see the enabled-plugin set.
• Pass enabled_plugins from LauncherApp into WidgetSettingsContext and DashboardContext in src/gui/mod.rs.
• Update plugin_names to filter returned plugin names by the enabled_plugins set when present.
• Enhance PinnedQueryResultsWidget to use the filtered engine list, show warnings and a fallback when the configured engine is disabled/missing, display a "No enabled engines available" notice, and add a guard in run_query that refuses to run against disabled engines.

Testing

• No automated tests were executed for this change.
• Changes are limited to UI plumbing and widget behavior; recommend running the app and exercising the dashboard editor and pinned query widget to validate UX and runtime behavior.

Codex Task