test: add comprehensive frontend tests for components, stores, and utils

Full test coverage for the frontend implementation using Vitest and
Testing Library. Tests are organized by concern with shared fixtures.

Component tests:
- AppShell.test.tsx: Navigation tabs, view switching, batch mode overlay
- FocusCard.test.tsx: Rendering, action buttons, keyboard shortcuts, empty state
- QueueView.test.tsx: Item display, focus promotion, empty state
- QueueItem.test.tsx: Type badges, click handling
- QueueSummary.test.tsx: Count display by type
- QuickCapture.test.tsx: Modal behavior, form submission, error states
- BatchMode.test.tsx: Progress tracking, item advancement, completion
- App.test.tsx: Updated for AppShell integration

Store tests:
- focus-store.test.ts: Item management, act(), setFocus(), reorderQueue()
- nav-store.test.ts: View switching
- capture-store.test.ts: Open/close, submission states
- batch-store.test.ts: Batch lifecycle, status tracking, derived counts

Library tests:
- types.test.ts: Type guards, staleness computation
- transform.test.ts: Lore data transformation, priority ordering
- format.test.ts: IID formatting for MRs vs issues

E2E tests (app.spec.ts):
- Navigation flow
- Focus card interactions
- Queue management
- Quick capture flow

Test infrastructure:
- fixtures.ts: makeFocusItem() factory
- tauri-plugin-shell.ts: Mock for @tauri-apps/plugin-shell
- Updated tauri-api.ts mock with new commands
- vitest.config.ts: Path aliases, jsdom environment
- playwright.config.ts: Removed webServer (run separately)
- package.json: Added @tauri-apps/plugin-shell dependency

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tests/stores/focus-store.test.ts

@@ -0,0 +1,192 @@
+import { describe, it, expect, beforeEach } from "vitest";
+import { useFocusStore } from "@/stores/focus-store";
+import { makeFocusItem } from "../helpers/fixtures";
+
+describe("useFocusStore", () => {
+  beforeEach(() => {
+    // Reset store between tests
+    useFocusStore.setState({
+      current: null,
+      queue: [],
+      isLoading: false,
+      error: null,
+    });
+  });
+
+  describe("setItems", () => {
+    it("sets first item as current and rest as queue", () => {
+      const items = [
+        makeFocusItem({ id: "a", title: "First" }),
+        makeFocusItem({ id: "b", title: "Second" }),
+        makeFocusItem({ id: "c", title: "Third" }),
+      ];
+
+      useFocusStore.getState().setItems(items);
+
+      const state = useFocusStore.getState();
+      expect(state.current?.id).toBe("a");
+      expect(state.queue).toHaveLength(2);
+      expect(state.queue[0].id).toBe("b");
+      expect(state.queue[1].id).toBe("c");
+    });
+
+    it("sets current to null when empty", () => {
+      useFocusStore.getState().setItems([]);
+
+      const state = useFocusStore.getState();
+      expect(state.current).toBeNull();
+      expect(state.queue).toHaveLength(0);
+    });
+
+    it("clears loading and error on setItems", () => {
+      useFocusStore.setState({ isLoading: true, error: "old error" });
+
+      useFocusStore.getState().setItems([makeFocusItem()]);
+
+      const state = useFocusStore.getState();
+      expect(state.isLoading).toBe(false);
+      expect(state.error).toBeNull();
+    });
+  });
+
+  describe("act", () => {
+    it("advances to next item in queue", () => {
+      useFocusStore.getState().setItems([
+        makeFocusItem({ id: "a" }),
+        makeFocusItem({ id: "b" }),
+        makeFocusItem({ id: "c" }),
+      ]);
+
+      const next = useFocusStore.getState().act("start");
+
+      expect(next?.id).toBe("b");
+      expect(useFocusStore.getState().current?.id).toBe("b");
+      expect(useFocusStore.getState().queue).toHaveLength(1);
+    });
+
+    it("returns null when queue is empty", () => {
+      useFocusStore.getState().setItems([makeFocusItem({ id: "only" })]);
+
+      const next = useFocusStore.getState().act("skip");
+
+      expect(next).toBeNull();
+      expect(useFocusStore.getState().current).toBeNull();
+      expect(useFocusStore.getState().queue).toHaveLength(0);
+    });
+
+    it("works with defer_1h action", () => {
+      useFocusStore.getState().setItems([
+        makeFocusItem({ id: "a" }),
+        makeFocusItem({ id: "b" }),
+      ]);
+
+      useFocusStore.getState().act("defer_1h", "in a meeting");
+
+      expect(useFocusStore.getState().current?.id).toBe("b");
+    });
+
+    it("works with defer_tomorrow action", () => {
+      useFocusStore.getState().setItems([
+        makeFocusItem({ id: "a" }),
+        makeFocusItem({ id: "b" }),
+      ]);
+
+      useFocusStore.getState().act("defer_tomorrow");
+
+      expect(useFocusStore.getState().current?.id).toBe("b");
+    });
+  });
+
+  describe("setFocus", () => {
+    it("promotes a queue item to current", () => {
+      useFocusStore.getState().setItems([
+        makeFocusItem({ id: "a", title: "First" }),
+        makeFocusItem({ id: "b", title: "Second" }),
+        makeFocusItem({ id: "c", title: "Third" }),
+      ]);
+
+      useFocusStore.getState().setFocus("c");
+
+      const state = useFocusStore.getState();
+      expect(state.current?.id).toBe("c");
+      // Previous current and other queue items are in queue
+      expect(state.queue.map((i) => i.id)).toEqual(
+        expect.arrayContaining(["a", "b"])
+      );
+      expect(state.queue).toHaveLength(2);
+    });
+
+    it("does nothing for unknown item ID", () => {
+      useFocusStore.getState().setItems([makeFocusItem({ id: "a" })]);
+
+      useFocusStore.getState().setFocus("nonexistent");
+
+      expect(useFocusStore.getState().current?.id).toBe("a");
+    });
+  });
+
+  describe("reorderQueue", () => {
+    it("moves an item from one position to another", () => {
+      useFocusStore.getState().setItems([
+        makeFocusItem({ id: "focus" }),
+        makeFocusItem({ id: "a" }),
+        makeFocusItem({ id: "b" }),
+        makeFocusItem({ id: "c" }),
+      ]);
+
+      useFocusStore.getState().reorderQueue(2, 0);
+
+      const ids = useFocusStore.getState().queue.map((i) => i.id);
+      expect(ids).toEqual(["c", "a", "b"]);
+    });
+
+    it("does nothing for same from/to index", () => {
+      useFocusStore.getState().setItems([
+        makeFocusItem({ id: "focus" }),
+        makeFocusItem({ id: "a" }),
+        makeFocusItem({ id: "b" }),
+      ]);
+
+      useFocusStore.getState().reorderQueue(0, 0);
+
+      const ids = useFocusStore.getState().queue.map((i) => i.id);
+      expect(ids).toEqual(["a", "b"]);
+    });
+
+    it("does nothing for out-of-bounds indices", () => {
+      useFocusStore.getState().setItems([
+        makeFocusItem({ id: "focus" }),
+        makeFocusItem({ id: "a" }),
+      ]);
+
+      useFocusStore.getState().reorderQueue(-1, 0);
+      useFocusStore.getState().reorderQueue(0, 5);
+
+      expect(useFocusStore.getState().queue.map((i) => i.id)).toEqual(["a"]);
+    });
+
+    it("does not affect current focus", () => {
+      useFocusStore.getState().setItems([
+        makeFocusItem({ id: "focus" }),
+        makeFocusItem({ id: "a" }),
+        makeFocusItem({ id: "b" }),
+      ]);
+
+      useFocusStore.getState().reorderQueue(1, 0);
+
+      expect(useFocusStore.getState().current?.id).toBe("focus");
+    });
+  });
+
+  describe("setLoading / setError", () => {
+    it("sets loading state", () => {
+      useFocusStore.getState().setLoading(true);
+      expect(useFocusStore.getState().isLoading).toBe(true);
+    });
+
+    it("sets error state", () => {
+      useFocusStore.getState().setError("something broke");
+      expect(useFocusStore.getState().error).toBe("something broke");
+    });
+  });
+});