feat: tool use — Lyra's first real actions (journal_write, note)

She can now *do* things mid-conversation, not just reply. Adds a tool-calling
loop to the chat path and her first two tools; the same mechanism will carry the
poker tools (start_session, log_result, get_stats, solver) next.

- tools.py: registry of OpenAI-style tool specs + handlers + safe dispatch;
  journal_write (knowing journaling) and note (tagged notepad, e.g. poker reads)
- llm.chat_call(): OpenAI-style call that returns tool_calls (cloud/mi50);
  local has no tool support and returns plain content
- chat.respond(): tool loop — offer tools, run any calls, feed results back,
  repeat until a text reply (capped at MAX_TOOL_ROUNDS); persists final reply
- tests: dispatch + full chat loop (tool call -> result -> reply)

Verified live: she invoked `note`, tagged it 'poker', stored a villain read.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lyra/llm.py

@@ -43,6 +43,43 @@ def complete(messages: list[Message], backend: Backend = "local", model: str | N
     return resp.json()["message"]["content"]
 
 
+def chat_call(
+    messages: list, backend: Backend = "cloud", model: str | None = None,
+    tools: list | None = None,
+) -> tuple[dict, list | None]:
+    """One chat turn that may request tool calls (OpenAI-style backends only).
+
+    Returns (assistant_message, tool_calls): `assistant_message` is the raw
+    message dict to append back to `messages` before any tool results;
+    `tool_calls` is a list of {id, name, arguments} or None. `local` (Ollama)
+    has no tool support here, so it just returns plain content.
+    """
+    cfg = load()
+    if backend in ("cloud", "mi50"):
+        if backend == "cloud":
+            if not cfg.openai_api_key:
+                raise RuntimeError("OPENAI_API_KEY is not set")
+            client = OpenAI(api_key=cfg.openai_api_key)
+            mdl = model or cfg.cloud_model
+        else:
+            client = OpenAI(api_key="not-needed", base_url=cfg.mi50_base_url)
+            mdl = model or cfg.mi50_model
+        kwargs: dict = {"model": mdl, "messages": messages}
+        if tools:
+            kwargs["tools"] = tools
+        msg = client.chat.completions.create(**kwargs).choices[0].message
+        tcs = None
+        if getattr(msg, "tool_calls", None):
+            tcs = [
+                {"id": tc.id, "name": tc.function.name, "arguments": tc.function.arguments}
+                for tc in msg.tool_calls
+            ]
+        return msg.model_dump(), tcs
+
+    # local (Ollama): no tool-calling here — return plain content.
+    return {"role": "assistant", "content": complete(messages, backend=backend, model=model)}, None
+
+
 def embed(texts: list[str]) -> list[list[float]]:
     """Embed texts using the configured backend (EMBED_BACKEND: "cloud" or "local").