feat: add multi-company batch processing

- Add CompanyAnalysisResult and BatchAnalysisResult dataclasses
- Implement analyze_companies() for concurrent batch analysis
- Implement analyze_companies_sequential() for rate-limited scenarios
- Add progress callback support for monitoring batch jobs
- Include 5 new tests for batch processing functionality
- Fix pre-existing test mock issue in test_llm.py

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

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

tests/test_llm.py

@@ -25,6 +25,8 @@ class TestLLMAnalyzer:
         mock_openai = mocker.patch("SPARC.llm.OpenAI")
         mock_config = mocker.patch("SPARC.llm.config")
         mock_config.openrouter_api_key = "config-key-456"
+        mock_config.use_database = False
+        mock_config.database_url = "postgresql://localhost/test"
 
         analyzer = LLMAnalyzer()