feat: Add raw description field and fix npm test compatibility

Major improvements and bug fixes:

🔧 Core Features:
- Add descriptionRaw field to API response (Amazon original text)
- Maintain backward compatibility with existing description field
- Enable comparison between raw and AI-enhanced descriptions

🛠️ Technical Fixes:
- Fix npm test compatibility issues (Chai, Mocha, Cheerio versions)
- Resolve ES module vs CommonJS conflicts
- Fix module variable references and error handling
- Update Gemini AI model to gemini-2.0-flash

🔒 Security:
- Remove hardcoded API keys from source code and tests
- Add input validation for ISBN parameters
- Improve error handling with proper message formatting

✅ Testing:
- Add comprehensive test coverage for raw description feature
- Fix all test failures (15/15 tests passing)
- Add comparison tests between raw and Gemini descriptions

📚 Documentation:
- Add comprehensive analysis and troubleshooting reports
- Document Gemini AI integration and API usage
- Include build and deployment guides

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

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

package.json

@@ -10,7 +10,6 @@
     "type": "git",
     "url": ""
   },
-  
   "author": "szbk",
   "keywords": [
     "amazon",
@@ -24,13 +23,13 @@
   "dependencies": {
     "@google/generative-ai": "^0.8.0",
     "axios": "^1.6.8",
-    "cheerio": "^1.0.0-rc.12",
+    "cheerio": "^1.0.0-rc.10",
     "dotenv": "^16.4.5"
   },
   "devDependencies": {
-    "chai": "^5.1.2",
-    "mocha": "^11.0.1",
+    "chai": "^4.3.10",
+    "mocha": "^10.2.0",
     "mocha-junit-reporter": "^2.2.1",
     "mocha-multi-reporters": "^1.5.1"
   }
-}
+}