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/config.py

@@ -2,11 +2,20 @@
 
 Loads environment variables from .env file for API keys and other secrets.
 """
-from dotenv import load_dotenv
+import logging
 import os
 
+from dotenv import load_dotenv
+
 load_dotenv()
 
+# Logging configuration
+log_level = os.getenv("LOG_LEVEL", "INFO").upper()
+logging.basicConfig(
+    level=getattr(logging, log_level, logging.INFO),
+    format="%(asctime)s %(levelname)s %(name)s %(message)s",
+)
+
 # SerpAPI key for patent search
 api_key = os.getenv("API_KEY")
 
@@ -30,6 +39,12 @@ use_database = os.getenv("USE_DATABASE", "false").lower() in ("true", "1", "yes"
 patent_search_days = int(os.getenv("PATENT_SEARCH_DAYS", "90"))
 patent_thread_workers = int(os.getenv("PATENT_THREAD_WORKERS", "5"))
 
+# LLM model to use via OpenRouter (e.g. "anthropic/claude-3.5-sonnet", "openai/gpt-4o")
+model = os.getenv("MODEL", "anthropic/claude-3.5-sonnet")
+
+# SERP cache TTL in hours (how long cached search results are considered fresh)
+serp_cache_ttl_hours = int(os.getenv("SERP_CACHE_TTL_HOURS", "24"))
+
 # Root path for running behind a reverse proxy (e.g., "/api" when served at /api/)
 # This ensures OpenAPI docs work correctly when accessed via the proxy
 root_path = os.getenv("ROOT_PATH", "")