feat(FN-3778): add reports plugin scaffold with notification service improv

The merge introduces a new `fusion-plugin-reports` plugin scaffold with settings schema, manifest, entry point, and tests, alongside a mobile session switcher in the chat header. It also adds a mailbox notifications system with ntfy/webhook providers, cleans up roadmap types from core, and includes

Fusion-Task-Id: FN-3778

plugins/fusion-plugin-reports/src/index.ts

@@ -0,0 +1,20 @@
+import { definePlugin } from "@fusion/plugin-sdk";
+import { settingsSchema } from "./settings.js";
+
+const plugin = definePlugin({
+  manifest: {
+    id: "fusion-plugin-reports",
+    name: "Reports",
+    version: "0.1.0",
+    description: "Generates beautiful HTML system-activity reports with multi-agent review.",
+    author: "Fusion Team",
+    fusionVersion: ">=0.1.0",
+    settingsSchema,
+  },
+  state: "installed",
+  hooks: {},
+});
+
+export default plugin;
+
+export * from "./settings.js";