**Add Vitest support and migrate frontend tests**

- Added Vitest configuration (`vitest.config.mjs`) for frontend unit testing with a `jsdom` environment.
- Migrated and rewrote key frontend tests (`api.test.js`, `comiclist.test.js`, `comicreader.test.js`, `historytable.test.js`, `router.test.js`, `store.test.js`) to Vitest, improving maintainability.
- Removed `tsconfig.json` and related TypeScript loaders from `webpack` configurations (`webpack.dev.js`, `webpack.prod.js`).
- Adjusted `eslint.config.mjs` to support Vitest tests.
- Updated `package-lock.json` to include Vitest, test utilities (`jsdom`, `@vue/test-utils`), and other associated packages.
- Updated Nginx configuration for better compression on assets (`gzip` adjustments).
- Enhanced `entrypoint.sh` to include first-run library indexing (`--if-empty` argument).
- Simplified the `scan_comics` command with a dedicated test for empty database scans.

This transition improves testing workflows and backend/frontend synergy while removing unused TypeScript dependencies.

frontend/test/api.test.js

@@ -0,0 +1,114 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+
+const { api, store, router, interceptors } = vi.hoisted(() => {
+  const interceptors = { request: [], response: [] }
+  const api = {
+    request: vi.fn(),
+    interceptors: {
+      request: { use: (fn) => interceptors.request.push(fn) },
+      response: { use: (ok, err) => interceptors.response.push({ ok, err }) },
+    },
+  }
+  return {
+    api,
+    store: { dispatch: vi.fn(), commit: vi.fn() },
+    router: { push: vi.fn() },
+    interceptors,
+  }
+})
+
+vi.mock('axios', () => ({ default: { create: () => api } }))
+vi.mock('@/store', () => ({ default: store }))
+vi.mock('@/router', () => ({ default: router }))
+
+import axiosApi from '@/api'
+
+const requestInterceptor = interceptors.request[0]
+const { ok: successHandler, err: errorHandler } = interceptors.response[0]
+
+function error401(url) {
+  return { response: { status: 401 }, config: { url } }
+}
+
+beforeEach(() => {
+  document.cookie = 'csrftoken=; path=/; expires=Thu, 01 Jan 1970 00:00:00 GMT'
+  api.request.mockReset()
+  store.dispatch.mockReset()
+  store.commit.mockReset()
+  router.push.mockReset()
+})
+
+describe('request interceptor', () => {
+  it('uses the cookie session, so it sends no Authorization header', () => {
+    expect(axiosApi).toBe(api)
+    expect(requestInterceptor({ headers: {} }).headers).not.toHaveProperty('Authorization')
+  })
+
+  it('adds the CSRF header when a csrftoken cookie exists', () => {
+    document.cookie = 'csrftoken=abc123; path=/'
+
+    expect(requestInterceptor({ headers: {} }).headers['X-CSRFToken']).toBe('abc123')
+  })
+
+  it('leaves the headers untouched when there is no CSRF cookie', () => {
+    expect(requestInterceptor({ headers: {} }).headers).not.toHaveProperty('X-CSRFToken')
+  })
+})
+
+describe('response interceptor', () => {
+  it('passes successful responses through', async () => {
+    const response = { data: [1, 2] }
+
+    expect(await successHandler(response)).toBe(response)
+    expect(store.dispatch).not.toHaveBeenCalled()
+  })
+
+  it('refreshes the session and retries once after a 401', async () => {
+    store.dispatch.mockResolvedValue(undefined)
+    api.request.mockResolvedValue({ data: 'retried' })
+    const error = error401('/api/browse/')
+
+    expect(await errorHandler(error)).toEqual({ data: 'retried' })
+    expect(store.dispatch).toHaveBeenCalledWith('refreshToken')
+    expect(api.request).toHaveBeenCalledWith(error.config)
+    expect(error.config._retried).toBe(true)
+  })
+
+  it('does not retry a request that has already been retried', async () => {
+    const error = error401('/api/browse/')
+    error.config._retried = true
+
+    await expect(errorHandler(error)).rejects.toBe(error)
+    expect(store.dispatch).not.toHaveBeenCalled()
+  })
+
+  it('does not retry the token endpoints, which would loop', async () => {
+    const error = error401('/api/token/refresh/')
+
+    await expect(errorHandler(error)).rejects.toBe(error)
+    expect(store.dispatch).not.toHaveBeenCalled()
+  })
+
+  it('logs out and goes to the login page when the refresh fails', async () => {
+    store.dispatch.mockRejectedValue(new Error('expired'))
+    const error = error401('/api/browse/')
+
+    await expect(errorHandler(error)).rejects.toBe(error)
+
+    expect(store.commit).toHaveBeenCalledWith('logOut')
+    expect(router.push).toHaveBeenCalledWith({
+      name: 'login',
+      query: {
+        next: '/api/browse/',
+        error: 'Your session has expired. Please log in again.',
+      },
+    })
+  })
+
+  it('leaves other error statuses alone', async () => {
+    const error = { response: { status: 403 }, config: { url: '/api/browse/' } }
+
+    await expect(errorHandler(error)).rejects.toBe(error)
+    expect(store.dispatch).not.toHaveBeenCalled()
+  })
+})