feat(FN-2339): add configurable ntfy server support

- Add ntfy base URL to global settings schema/types with persistence coverage and regression tests
- Extend dashboard settings API/routes and Settings modal UI to edit and save a custom ntfy server
- Update notifier runtime to use configured ntfy base URL when sending notifications
- Document the new setting and include a changeset for @runfusion/fusion

docs/settings-reference.md

@@ -40,6 +40,7 @@ Defaults from `DEFAULT_GLOBAL_SETTINGS`; key scope from `GLOBAL_SETTINGS_KEYS`.
 | `defaultThinkingLevel` | `"off" \| "minimal" \| "low" \| "medium" \| "high"` | `undefined` | Default reasoning effort for AI sessions. |
 | `ntfyEnabled` | `boolean` | `false` | Enable ntfy push notifications. |
 | `ntfyTopic` | `string` | `undefined` | ntfy topic name. |
+| `ntfyBaseUrl` | `string` | `undefined` | Optional custom ntfy server base URL (must use `http://` or `https://`). If blank/unset, Fusion uses `https://ntfy.sh` for both runtime and test notifications. |
 | `ntfyEvents` | `("in-review" \| "merged" \| "failed" \| "awaiting-approval" \| "awaiting-user-review" \| "planning-awaiting-input")[]` | `["in-review","merged","failed","awaiting-approval","awaiting-user-review","planning-awaiting-input"]` | Event types that trigger ntfy notifications. `planning-awaiting-input` fires when planning mode is waiting on user input. |
 | `ntfyDashboardHost` | `string` | `undefined` | Dashboard host used to build deep links in notifications. |
 | `defaultProjectId` | `string` | `undefined` | Default project for multi-project CLI operations when `--project` is omitted. |