feat(FN-669): add ntfy deep link support for dashboard notifications

- Add ntfyDashboardHost setting to GlobalSettings for dashboard URL
- Generate deep link URLs in ntfy notifications with Click header
- Add tests for deep link generation with various URL scenarios
- Handle ?task= query param in dashboard for deep linking
- Add dashboard hostname UI in settings modal with validation

packages/core/src/types.ts

@@ -535,6 +535,10 @@ export interface GlobalSettings {
    *  no project can be auto-detected from the current directory.
    *  Used for multi-project CLI workflows. */
   defaultProjectId?: string;
+  /** Dashboard hostname for ntfy.sh deep links. When set along with ntfyEnabled
+   *  and ntfyTopic, notifications include a Click URL that opens the dashboard
+   *  directly to the task. Example: "http://localhost:3000" or "https://fusion.example.com" */
+  ntfyDashboardHost?: string;
 }
 
 /**
@@ -695,6 +699,7 @@ export const DEFAULT_GLOBAL_SETTINGS: Required<Pick<GlobalSettings, "themeMode"
   ntfyEnabled: false,
   ntfyTopic: undefined,
   defaultProjectId: undefined,
+  ntfyDashboardHost: undefined,
 };
 
 /** Default values for project-level settings. */
@@ -754,6 +759,7 @@ export const GLOBAL_SETTINGS_KEYS: ReadonlyArray<keyof GlobalSettings> = [
   "ntfyEnabled",
   "ntfyTopic",
   "defaultProjectId",
+  "ntfyDashboardHost",
 ] as const;
 
 /** Keys that belong to the project settings scope. */