feat(KB-074): add quick task creation with QuickEntryBox and NewTaskModal

- Add QuickEntryBox component for inline quick task entry in columns
- Add NewTaskModal component with full-featured task creation UI
- Integrate quick create flow through Column → Board → App component hierarchy
- Add comprehensive tests for both new components and updated existing tests
- Add CSS styles for modal, form inputs, and quick entry UI
- Include changeset for @dustinbyrne/kb package release

packages/dashboard/app/components/__tests__/QuickEntryBox.test.tsx

@@ -0,0 +1,154 @@
+import { describe, it, expect, vi } from "vitest";
+import { render, screen, fireEvent, waitFor } from "@testing-library/react";
+import { QuickEntryBox } from "../QuickEntryBox";
+
+function renderQuickEntryBox() {
+  const props = {
+    onCreate: vi.fn().mockResolvedValue(undefined),
+    addToast: vi.fn(),
+  };
+  const result = render(<QuickEntryBox {...props} />);
+  return { ...result, props };
+}
+
+describe("QuickEntryBox", () => {
+  it("renders input with placeholder", () => {
+    renderQuickEntryBox();
+    const input = screen.getByTestId("quick-entry-input");
+    expect(input).toBeTruthy();
+    expect(input.placeholder).toBe("Add a task...");
+  });
+
+  it("creates task on Enter key", async () => {
+    const { props } = renderQuickEntryBox();
+    const input = screen.getByTestId("quick-entry-input");
+
+    fireEvent.change(input, { target: { value: "New task description" } });
+    fireEvent.keyDown(input, { key: "Enter" });
+
+    await waitFor(() => {
+      expect(props.onCreate).toHaveBeenCalledWith("New task description");
+    });
+  });
+
+  it("shows loading state during creation", async () => {
+    const { props } = renderQuickEntryBox();
+    // Slow down the promise to see loading state
+    props.onCreate.mockImplementation(() => new Promise((resolve) => setTimeout(resolve, 100)));
+
+    const input = screen.getByTestId("quick-entry-input");
+    fireEvent.change(input, { target: { value: "New task" } });
+    fireEvent.keyDown(input, { key: "Enter" });
+
+    // Check loading placeholder
+    await waitFor(() => {
+      expect(input.placeholder).toBe("Creating...");
+    });
+
+    // Input should be disabled during creation
+    expect(input).toBeDisabled();
+  });
+
+  it("clears input after successful creation", async () => {
+    const { props } = renderQuickEntryBox();
+    const input = screen.getByTestId("quick-entry-input");
+
+    fireEvent.change(input, { target: { value: "Task to create" } });
+    fireEvent.keyDown(input, { key: "Enter" });
+
+    await waitFor(() => {
+      expect(props.onCreate).toHaveBeenCalled();
+    });
+
+    expect(input.value).toBe("");
+  });
+
+  it("shows error toast on failure and keeps input content", async () => {
+    const { props } = renderQuickEntryBox();
+    props.onCreate.mockRejectedValue(new Error("Network error"));
+
+    const input = screen.getByTestId("quick-entry-input");
+    fireEvent.change(input, { target: { value: "Failed task" } });
+    fireEvent.keyDown(input, { key: "Enter" });
+
+    await waitFor(() => {
+      expect(props.addToast).toHaveBeenCalledWith("Network error", "error");
+    });
+
+    // Input content should be preserved for retry
+    expect(input.value).toBe("Failed task");
+  });
+
+  it("clears non-empty input on Escape key", () => {
+    renderQuickEntryBox();
+    const input = screen.getByTestId("quick-entry-input");
+
+    fireEvent.change(input, { target: { value: "Some text" } });
+    expect(input.value).toBe("Some text");
+
+    fireEvent.keyDown(input, { key: "Escape" });
+    expect(input.value).toBe("");
+  });
+
+  it("does not clear empty input on Escape key", () => {
+    renderQuickEntryBox();
+    const input = screen.getByTestId("quick-entry-input");
+
+    fireEvent.keyDown(input, { key: "Escape" });
+    expect(input.value).toBe("");
+  });
+
+  it("does not submit on Enter if input is empty", async () => {
+    const { props } = renderQuickEntryBox();
+    const input = screen.getByTestId("quick-entry-input");
+
+    fireEvent.keyDown(input, { key: "Enter" });
+
+    // Wait a bit to ensure no async call happens
+    await new Promise((resolve) => setTimeout(resolve, 50));
+
+    expect(props.onCreate).not.toHaveBeenCalled();
+  });
+
+  it("does not submit on Enter if input is only whitespace", async () => {
+    const { props } = renderQuickEntryBox();
+    const input = screen.getByTestId("quick-entry-input");
+
+    fireEvent.change(input, { target: { value: "   " } });
+    fireEvent.keyDown(input, { key: "Enter" });
+
+    await new Promise((resolve) => setTimeout(resolve, 50));
+
+    expect(props.onCreate).not.toHaveBeenCalled();
+  });
+
+  it("prevents default on Enter key", () => {
+    renderQuickEntryBox();
+    const input = screen.getByTestId("quick-entry-input");
+
+    fireEvent.change(input, { target: { value: "Task" } });
+    const prevented = !fireEvent.keyDown(input, { key: "Enter" });
+
+    expect(prevented).toBe(true);
+  });
+
+  it("updates input value on change", () => {
+    renderQuickEntryBox();
+    const input = screen.getByTestId("quick-entry-input");
+
+    fireEvent.change(input, { target: { value: "Updated text" } });
+    expect(input.value).toBe("Updated text");
+  });
+
+  it("trims whitespace when creating task", async () => {
+    const { props } = renderQuickEntryBox();
+    const input = screen.getByTestId("quick-entry-input");
+
+    fireEvent.change(input, { target: { value: "  Task with spaces  " } });
+    fireEvent.keyDown(input, { key: "Enter" });
+
+    await waitFor(() => {
+      expect(props.onCreate).toHaveBeenCalledWith("Task with spaces");
+    });
+  });
+});