refactor: remediation plan Fase 0-4 completata

- Fase 0: env var allineate, SYSTEM_PROMPT deduplicato, .gitignore pulito
- Fase 1: GameContext isolato, ciclo DM unificato, provider thread-safe (contextvars)
- Fase 2: DB schema esteso (current_area_id, combat_state, character_items)
- Fase 3: thread-local connection pool + WAL + busy_timeout
- Fase 4: test suite (32 test, 100% pass)
- heuristic_fallback come parser di riserva (non secondo pilota)

src/engine/config.py

@@ -13,6 +13,7 @@ class ProviderConfig:
     ollama_model: str = "gemma2:9b"
     openrouter_api_key: str = ""
     openrouter_model: str = "openrouter/free"
+    openrouter_key_env: str = "DCC_OPENROUTER_KEY"
     openrouter_free_fallback: bool = True
     local_base_url: str = "http://192.168.0.240/v1"
     local_api_key: str = ""
@@ -25,7 +26,7 @@ def load_from_env() -> ProviderConfig:
         kind=os.getenv("DCC_LLM_PROVIDER", "openrouter"),  # type: ignore
         ollama_base_url=os.getenv("DCC_OLLAMA_URL", "http://192.168.0.50:11434"),
         ollama_model=os.getenv("DCC_OLLAMA_MODEL", "gemma2:9b"),
-        openrouter_api_key=os.getenv("OPENROUTER_API_KEY", ""),
+        openrouter_api_key=os.getenv("DCC_OPENROUTER_KEY", os.getenv("OPENROUTER_API_KEY", "")),
         openrouter_model=os.getenv("DCC_OPENROUTER_MODEL", "openrouter/free"),
         openrouter_free_fallback=os.getenv("DCC_OR_FREE_FALLBACK", "1") == "1",
         local_base_url=os.getenv("DCC_LOCAL_URL", "http://192.168.0.240/v1"),