feat: configurable LLM model, SERP cache TTL, structured logging, fix patent_id type

- Make LLM model configurable via MODEL env var, default anthropic/claude-3.5-sonnet (#12)
- Expose SERP cache TTL as SERP_CACHE_TTL_HOURS env var, default 24 hours (#13)
- Fix Patent.patent_id type annotation from int to str in types.py (#14)
- Replace all print() calls with structured logging in analyzer.py and llm.py (#11)
- Add LOG_LEVEL config with basicConfig setup in config.py
- Add model and serp_cache_ttl_hours to config.py

Closes leeworks-agents/SPARC#11
Closes leeworks-agents/SPARC#12
Closes leeworks-agents/SPARC#13
Closes leeworks-agents/SPARC#14

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

SPARC/llm.py

@@ -1,9 +1,14 @@
 """LLM integration for patent analysis using OpenRouter."""
 
+import logging
+from typing import Dict
+
 from openai import OpenAI
+
 from SPARC import config
 from SPARC.database import DatabaseClient
-from typing import Dict
+
+logger = logging.getLogger(__name__)
 
 
 class LLMAnalyzer:
@@ -20,7 +25,7 @@ class LLMAnalyzer:
         """
         self.test_mode = test_mode
         self.use_cache = use_cache if use_cache is not None else config.use_cache
-        self.model = "anthropic/claude-3.5-sonnet"
+        self.model = config.model
 
         # Always initialize database client for storage and caching
         self.db_client = DatabaseClient(config.database_url)
@@ -59,11 +64,7 @@ Patent Content:
 Provide a concise analysis (2-3 paragraphs) focusing on what this patent reveals about the company's technical direction and competitive advantage."""
 
         if self.test_mode:
-            print("=" * 80)
-            print("TEST MODE - Prompt that would be sent to LLM:")
-            print("=" * 80)
-            print(prompt)
-            print("=" * 80)
+            logger.debug("TEST MODE - Prompt that would be sent to LLM:\n%s", prompt)
             return "[TEST MODE - No API call made]"
 
         # Check cache first
@@ -165,7 +166,7 @@ Patent Portfolio:
 Provide a comprehensive analysis (4-5 paragraphs) with a final verdict on the company's innovation strength and performance outlook."""
 
         if self.test_mode:
-            print(prompt)
+            logger.debug("TEST MODE - Portfolio prompt:\n%s", prompt)
             return "[TEST MODE]"
 
         metadata = {