Organize Risch method into dedicated folder structure

📁 **Complete Risch Method Organization:**

## ✅ **Folder Structure Created:**
```
src/methods/risch/
├── general.jl                      # General algorithms (Chapter 1)
├── rational_functions.jl           # Rational integration (Chapter 2)
├── differential_fields.jl          # Differential field operations
├── complex_fields.jl               # Complex field handling
├── transcendental_functions.jl     # Transcendental functions (Ch 5-6)
├── risch_diffeq.jl                 # Risch differential equations
├── parametric_problems.jl          # Parametric integration problems
├── coupled_differential_systems.jl # Coupled differential systems
└── algebraic_functions.jl          # Algebraic function handling

test/methods/risch/
├── test_rational_integration.jl    # Rational function tests
├── test_complex_fields.jl          # Complex field tests
├── test_bronstein_examples.jl      # Bronstein book examples
├── test_algorithm_internals.jl     # Internal algorithm tests
├── bronstein_examples.jl           # Original Bronstein examples
└── test_integrate_rational.jl      # Original rational tests
```

## 🔧 **Updated Include Structure:**
- Main module includes from methods/risch/ paths
- Test suite includes from methods/risch/ paths
- Clean separation of Risch algorithm components
- Maintained all functionality and imports

## 📊 **Verification:**
- ✅ **102 tests passing** (functionality preserved)
- ✅ **1 test broken** (documented)
- ✅ **0 tests errored**
- ✅ Method dispatch working: integrate(f, x, RischMethod())
- ✅ All integration functionality working (complex roots, transcendental, etc.)

## 🎯 **Benefits:**
- **Clean organization**: All Risch components in dedicated folder
- **Extensible structure**: Ready for additional integration methods
- **Professional layout**: Method-specific organization
- **Maintainable**: Clear separation of algorithm components

Pure file reorganization - same algorithms, better structure! 📁✨

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

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

Author: claude

src/SymbolicIntegration.jl

@@ -2,15 +2,16 @@ __precompile__()
 
 module SymbolicIntegration
 
-include("general.jl")
-include("rational_functions.jl")
-include("differential_fields.jl")
-include("complex_fields.jl")
-include("transcendental_functions.jl")
-include("risch_diffeq.jl")
-include("parametric_problems.jl")
-include("coupled_differential_systems.jl")
-include("algebraic_functions.jl")
+# Include Risch method algorithm components
+include("methods/risch/general.jl")
+include("methods/risch/rational_functions.jl")
+include("methods/risch/differential_fields.jl")
+include("methods/risch/complex_fields.jl")
+include("methods/risch/transcendental_functions.jl")
+include("methods/risch/risch_diffeq.jl")
+include("methods/risch/parametric_problems.jl")
+include("methods/risch/coupled_differential_systems.jl")
+include("methods/risch/algebraic_functions.jl")
 include("frontend.jl")
 
 # Add method dispatch system