feat: Add comprehensive testing infrastructure

- Add GitHub Actions CI/CD workflow (.github/workflows/ci.yml)
  * Multi-platform testing (Ubuntu, Windows, macOS)
  * Qt 6.5.0+ compatibility
  * Automated test execution with CTest
  * Code coverage reporting

- Restructure testing directories:
  * manual-testing/ - Easy manual tests with Qt Creator integration
  * tests/ - Professional QTest framework for CI/CD

- Add QTest-based unit tests:
  * test_diff.cpp - Core diff algorithm validation
  * test_patch.cpp - Patch creation and application
  * test_match.cpp - Fuzzy matching operations
  * test_edge_cases.cpp - Boundary conditions and error handling

- Add performance benchmarks:
  * test_performance.cpp - Algorithm speed and efficiency testing
  * Real-world scenario testing (code, config files, Unicode)
  * Noise sensitivity analysis

- Add memory tests:
  * test_memory.cpp - Memory usage and leak detection
  * Large file memory efficiency testing

- Improve manual testing:
  * Updated README with Qt Creator instructions
  * Optimized console output with std::cout
  * Progress indicators for long operations
  * Professional formatting and error handling

- Remove duplicate files and clean up structure
- All tests compatible with CTest for CI integration

Author: djad04

.github/workflows/ci.yml

@@ -0,0 +1,92 @@
+name: CI
+
+on:
+  push:
+    branches: [ main, develop ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  test:
+    name: Test on ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
+        qt-version: ['6.5.0']
+        
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v4
+      
+    - name: Install Qt
+      uses: jurplel/install-qt-action@v3
+      with:
+        version: ${{ matrix.qt-version }}
+        modules: 'qtbase'
+        
+    - name: Configure CMake
+      run: |
+        cd tests
+        cmake -B build -DCMAKE_BUILD_TYPE=Release
+        
+    - name: Build tests
+      run: |
+        cd tests
+        cmake --build build --config Release
+        
+    - name: Run tests
+      run: |
+        cd tests
+        ctest --test-dir build --output-on-failure --verbose
+        
+    - name: Upload test results
+      uses: actions/upload-artifact@v3
+      if: failure()
+      with:
+        name: test-results-${{ matrix.os }}
+        path: tests/build/Testing/
+        
+  coverage:
+    name: Code Coverage
+    runs-on: ubuntu-latest
+    if: github.event_name == 'push'
+    
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v4
+      
+    - name: Install Qt
+      uses: jurplel/install-qt-action@v3
+      with:
+        version: '6.5.0'
+        modules: 'qtbase'
+        
+    - name: Install coverage tools
+      run: |
+        sudo apt-get update
+        sudo apt-get install -y gcov lcov
+        
+    - name: Configure CMake with coverage
+      run: |
+        cd tests
+        cmake -B build -DCMAKE_BUILD_TYPE=Debug -DCMAKE_CXX_FLAGS="--coverage"
+        
+    - name: Build and test with coverage
+      run: |
+        cd tests
+        cmake --build build
+        ctest --test-dir build --output-on-failure
+        
+    - name: Generate coverage report
+      run: |
+        cd tests
+        lcov --capture --directory build --output-file coverage.info
+        lcov --remove coverage.info '/usr/*' --output-file coverage.info
+        lcov --list coverage.info
+        
+    - name: Upload coverage to Codecov
+      uses: codecov/codecov-action@v3
+      with:
+        file: tests/coverage.info
+        fail_ci_if_error: false