fix: add free-code to provider validator to suppress 'Unknown provider' warning

helpers.py validation map lacked the free-code entry, causing a spurious
warning before every run. free-code requires no env vars (proxy to claude serve),
so its entry has an empty list — missing_vars stays empty, no warning emitted.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: dmikushin

packages/cli/src/repowise/cli/helpers.py

@@ -316,12 +316,14 @@ def _is_env_var_exists(var_name: str) -> bool:
         return var_name in os.environ
 
     # Define required environment variables for each provider
+    # Providers with an empty list need no env vars (they work out of the box)
     provider_env_vars = {
         "anthropic": ["ANTHROPIC_API_KEY"],
         "openai": ["OPENAI_API_KEY"],
         "gemini": ["GEMINI_API_KEY", "GOOGLE_API_KEY"],  # Either one
         "ollama": ["OLLAMA_BASE_URL"],
         "litellm": ["LITELLM_API_KEY"],  # May need others depending on backend
+        "free-code": [],  # No key needed — uses claude serve proxy
     }
 
     if provider_name: