Sidebar tab API for extensions (#215)

* Add extensionManager to manage tabs

* Fix null bug

* nit

src/stores/workspaceStateStore.ts

@@ -0,0 +1,32 @@
+import { defineStore } from "pinia";
+
+interface WorkspaceState {
+  activeSidebarTab: string | null;
+  sidebarTabsOrder: string[]; // Array of tab IDs in order
+}
+
+export const useWorkspaceStore = defineStore("workspace", {
+  state: (): WorkspaceState => ({
+    activeSidebarTab: null,
+    sidebarTabsOrder: [],
+  }),
+  actions: {
+    updateActiveSidebarTab(tabId: string) {
+      this.activeSidebarTab = tabId;
+    },
+    updateSidebarOrder(newOrder: string[]) {
+      this.sidebarTabsOrder = newOrder;
+    },
+    serialize() {
+      return JSON.stringify({
+        activeSidebarTab: this.activeSidebarTab,
+        sidebarTabsOrder: this.sidebarTabsOrder,
+      });
+    },
+    deserialize(state: string) {
+      const parsedState = JSON.parse(state);
+      this.sidebarTabsOrder = parsedState.sidebarTabsOrder;
+      this.activeSidebarTab = parsedState.activeSidebarTab;
+    },
+  },
+});