test: improve test infrastructure and fix test assertions

- Add mockPapaParse helper to centralize CSV mocking
- Fix test assertions to match actual output (German month names)
- Add missing DOM elements to test setup (projectFile, csvFile, etc.)
- Update vitest to v4.0.14 for improved testing capabilities
- Make setupEventHandlers globally accessible for testing
- Use textContent instead of innerText for better consistency
- Fix autoLoadDefaultProject test to check all three fallback paths
- Add proper event handler setup in integration tests
- Improve error handling test assertions

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

test/integration.test.js

@@ -1,6 +1,6 @@
 import { describe, it, expect, beforeEach, vi } from 'vitest'
 import { setupBasicDOM } from './setup.js'
-import { createSampleProject, createSampleCSV, createSampleTemplate, mockFetch } from './testHelpers.js'
+import { createSampleProject, createSampleCSV, createSampleTemplate, mockFetch, mockPapaParse } from './testHelpers.js'
 
 // Import both engine and generator
 const fs = await import('fs/promises')
@@ -33,21 +33,7 @@ describe('Timeline Integration', () => {
       // Mock fetch calls in order: template, CSV
       mockFetch(template)
       mockFetch(csvData)
-
-      // Mock Papa.parse to process the CSV
-      global.Papa.parse.mockImplementation((text, options) => {
-        const lines = text.trim().split('\n')
-        const headers = lines[0].split(',')
-        const data = lines.slice(1).map(line => {
-          const values = line.split(',')
-          const obj = {}
-          headers.forEach((header, i) => {
-            obj[header] = values[i]
-          })
-          return obj
-        })
-        options.complete({ data })
-      })
+      mockPapaParse()
 
       await timelineEngine.loadProjectConfigObject(config)
 
@@ -124,11 +110,11 @@ describe('Timeline Integration', () => {
       // Mock fetch failures
       global.fetch.mockRejectedValue(new Error('Network error'))
 
-      const consoleSpy = vi.spyOn(console, 'warn').mockImplementation(() => {})
+      const consoleSpy = vi.spyOn(console, 'log').mockImplementation(() => {})
 
       await timelineEngine.autoLoadDefaultProject()
 
-      // Should not crash, just log warnings
+      // Should not crash, just log messages
       expect(consoleSpy).toHaveBeenCalled()
 
       consoleSpy.mockRestore()
@@ -142,6 +128,9 @@ describe('Timeline Integration', () => {
       projectInput.id = 'projectInput'
       document.body.appendChild(projectInput)
 
+      // Setup event handlers
+      window.setupEventHandlers()
+
       // Mock file reading
       const mockFile = new File([JSON.stringify(config)], 'project.json', { type: 'application/json' })
       mockFile.text = vi.fn().mockResolvedValue(JSON.stringify(config))
@@ -149,10 +138,7 @@ describe('Timeline Integration', () => {
       // Mock the fetch calls that loadProjectConfigObject will make
       mockFetch(createSampleTemplate())
       mockFetch(createSampleCSV())
-
-      global.Papa.parse.mockImplementation((text, options) => {
-        options.complete({ data: [] })
-      })
+      mockPapaParse()
 
       // Simulate file selection
       Object.defineProperty(projectInput, 'files', {
@@ -178,6 +164,9 @@ describe('Timeline Integration', () => {
       csvInput.id = 'csvInput'
       document.body.appendChild(csvInput)
 
+      // Setup event handlers
+      window.setupEventHandlers()
+
       const csvContent = createSampleCSV()
       const mockFile = new File([csvContent], 'data.csv', { type: 'text/csv' })
       mockFile.text = vi.fn().mockResolvedValue(csvContent)