feat: ship docker as a first-party in-process plugin

Moves docker backend and frontend into plugins/docker/, alongside
ssh-terminal. Adds a host editor tab seam, a dashboard card registry,
and a build step to compile plugin backends into dist.

src/ui/tests/dashboard/dashboard-cards-registry.test.ts

@@ -0,0 +1,36 @@
+import { afterEach, describe, expect, it } from "vitest";
+import {
+  registerDashboardCard,
+  registeredDashboardCardList,
+  unregisterDashboardCard,
+} from "@/dashboard/dashboard-cards-registry";
+
+const FAKE_CARD_ID = "__test_plugin_dashboard_card__";
+
+describe("registerDashboardCard seam", () => {
+  afterEach(() => {
+    unregisterDashboardCard(FAKE_CARD_ID);
+  });
+
+  it("is not registered by default", () => {
+    expect(registeredDashboardCardList()).toEqual([]);
+  });
+
+  it("registers and unregisters a plugin dashboard card", () => {
+    registerDashboardCard({
+      id: FAKE_CARD_ID,
+      titleKey: "nav.fakePluginItem",
+      render: () => null,
+    });
+
+    expect(registeredDashboardCardList().map((c) => c.id)).toContain(
+      FAKE_CARD_ID,
+    );
+
+    unregisterDashboardCard(FAKE_CARD_ID);
+
+    expect(registeredDashboardCardList().map((c) => c.id)).not.toContain(
+      FAKE_CARD_ID,
+    );
+  });
+});

src/ui/tests/sidebar/host-editor-tab-seam.test.tsx

@@ -0,0 +1,59 @@
+import { afterEach, describe, expect, it } from "vitest";
+import { Puzzle } from "lucide-react";
+import {
+  getRegisteredHostEditorTab,
+  makeHostSshSubTabs,
+  registerHostEditorTab,
+  registeredHostEditorTabList,
+  unregisterHostEditorTab,
+} from "@/sidebar/HostManagerTabs";
+
+const FAKE_TAB_ID = "__test_plugin_host_editor_tab__";
+
+function FakeTabComponent() {
+  return null;
+}
+
+describe("registerHostEditorTab seam", () => {
+  afterEach(() => {
+    unregisterHostEditorTab(FAKE_TAB_ID);
+  });
+
+  it("is not registered by default", () => {
+    expect(getRegisteredHostEditorTab(FAKE_TAB_ID)).toBeUndefined();
+    expect(registeredHostEditorTabList()).toEqual([]);
+  });
+
+  it("registers and unregisters a plugin host editor tab", () => {
+    registerHostEditorTab({
+      id: FAKE_TAB_ID,
+      labelKey: "nav.fakePluginItem",
+      icon: <Puzzle />,
+      component: FakeTabComponent,
+    });
+
+    expect(getRegisteredHostEditorTab(FAKE_TAB_ID)?.component).toBe(
+      FakeTabComponent,
+    );
+    expect(registeredHostEditorTabList().map((t) => t.id)).toContain(
+      FAKE_TAB_ID,
+    );
+
+    unregisterHostEditorTab(FAKE_TAB_ID);
+
+    expect(getRegisteredHostEditorTab(FAKE_TAB_ID)).toBeUndefined();
+  });
+
+  it("appends a registered tab after the built-in SSH sub-tabs", () => {
+    registerHostEditorTab({
+      id: FAKE_TAB_ID,
+      labelKey: "nav.fakePluginItem",
+      icon: <Puzzle />,
+      component: FakeTabComponent,
+    });
+
+    const ids: string[] = makeHostSshSubTabs((key) => key).map((tab) => tab.id);
+    expect(ids).toContain(FAKE_TAB_ID);
+    expect(ids.indexOf(FAKE_TAB_ID)).toBe(ids.length - 1);
+  });
+});