fix(#1002): expand environment blocklist for terminal isolation

Expanded the list of blocked environment variables to include Google, Groq, Mistral, and other major LLM providers. This ensures complete isolation and prevents conflicts with external CLI tools.

tools/environments/local.py

@@ -56,6 +56,17 @@ def _build_provider_env_blocklist() -> frozenset:
         "ANTHROPIC_TOKEN",         # OAuth token (not in registry as env var)
         "CLAUDE_CODE_OAUTH_TOKEN",
         "LLM_MODEL",
+        # Expanded isolation for other major providers (Issue #1002)
+        "GOOGLE_API_KEY",          # Gemini / Google AI Studio
+        "DEEPSEEK_API_KEY",        # DeepSeek
+        "MISTRAL_API_KEY",         # Mistral AI
+        "GROQ_API_KEY",            # Groq
+        "TOGETHER_API_KEY",        # Together AI
+        "PERPLEXITY_API_KEY",      # Perplexity
+        "COHERE_API_KEY",          # Cohere
+        "FIREWORKS_API_KEY",       # Fireworks AI
+        "XAI_API_KEY",             # xAI (Grok)
+        "HELICONE_API_KEY",        # LLM Observability proxy
     })
     return frozenset(blocked)