Recognize Gemma as tool-capable

Gemma models (gemma-2/3/4) support OpenAI-style function calling, but
"gemma" was missing from the _model_supports_tools heuristic in
stream_agent_loop(). On a non-allowlisted endpoint (e.g. a self-hosted
OpenAI-compatible server), a Gemma-backed agent therefore never receives
native tool schemas and falls back to the prompt-text tool-call
convention — which Gemma does not follow. The result is that tool calls
are emitted as raw text and never execute.

Add "gemma" to the capability keyword list alongside the other
tool-capable families.

Co-authored-by: 2revoemag <2revoemag@users.noreply.github.com>
Co-authored-by: Claude <noreply@anthropic.com>

src/agent_loop.py

@@ -1358,7 +1358,7 @@ async def stream_agent_loop(
     except Exception as _e:
         logger.debug(f"endpoint supports_tools lookup failed: {_e}")
     _model_supports_tools = any(kw in _model_lc for kw in (
-        "deepseek", "gpt-4", "gpt-5", "gpt-o", "claude", "gemini",
+        "deepseek", "gpt-4", "gpt-5", "gpt-o", "claude", "gemini", "gemma",
         "qwen3", "qwen2.5", "mixtral", "mistral", "llama-3.1", "llama-3.2",
         "llama-3.3", "llama-4",
         # Local-served models that follow OpenAI-style function calling