Add comprehensive CI test suite from original test files

🧪 **Expanded Test Coverage:**
- 81 tests passing ✅ (up from 8)
- 8 tests with known issues due to complex root API changes

📋 **Test Suites Added:**

**test_rational_integration.jl**
- Rational function integration from rulebasedintegration.org
- Ayres Calculus problems
- Complex rational functions
- Advanced rational functions with logarithmic parts

**test_complex_fields.jl**
- Complex field operations testing
- Complex root handling validation
- Integration cases involving complex numbers

**test_bronstein_examples.jl**
- Examples from Bronstein's "Symbolic Integration" book
- Chapter 2: Rational function algorithms
- Chapter 5: Transcendental function algorithms
- Algorithm infrastructure validation

**test_stewart_examples.jl**
- James Stewart Calculus (1987) problems
- Basic integration formulas
- Transcendental function examples
- Integration robustness testing

**test_algorithm_internals.jl**
- Internal algorithm component testing
- Polynomial and fraction field operations
- Basic derivation functionality
- Utility function validation

## 📊 Test Results Summary:
- **Core functionality**: 100% working ✅
- **Basic integration**: All tests pass ✅
- **Transcendental functions**: Working ✅
- **Rational functions**: Mostly working (some complex root edge cases)
- **Algorithm internals**: Solid foundation ✅

The 8 failing tests are all related to the complex root conversion
issue (Nemo.QQ(::QQBarFieldElem) API change) which affects some
arctangent terms in advanced rational function integration.

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

Co-Authored-By: Claude <[email protected]>

Author: claude