feat: full-fidelity conversation export (chat + tool calls)

Chat only ever lived in SQLite's `exchanges` table (what was *said*); tool
calls were transient — logged to the in-memory ring buffer and gone at
end-of-turn. This adds a persistent record of what Lyra *did* and exports the
two merged into one transcript.

- memory: new `tool_events` table + `add_tool_event`/`tool_events` accessors;
  `delete_session` cascades to it.
- chat: persist each tool call (name/args/result) right where it fires, in both
  the non-stream and stream paths. Move the user `remember` to just after
  assembly so its timestamp precedes mid-turn tool events — keeps the export in
  true chronological order (and records when the message actually arrived).
- transcript: new module renders a session as Markdown (Brian/Lyra speech with
  ⚙ tool-call lines interleaved) or JSON (machine-readable event stream).
- server: GET /sessions/{id}/export?format=md|json (attachment download).
- ui: ⬇ Export button by the session selector (Markdown or JSON).

Doubles as the receipt for "did the tool actually fire?" — the thing that was
invisible when she'd reply about a hand without logging it.

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

tests/test_transcript.py

@@ -0,0 +1,82 @@
+"""Conversation export: speech (exchanges) + actions (tool_events) merged in order."""
+from __future__ import annotations
+
+import importlib
+import json
+
+import pytest
+
+
+def _const_embed(texts):
+    return [[1e-6] * 8 for _ in texts]
+
+
+@pytest.fixture
+def mods(tmp_path, monkeypatch):
+    monkeypatch.setenv("LYRA_DB_PATH", str(tmp_path / "test.db"))
+    from lyra import llm
+    monkeypatch.setattr(llm, "embed", _const_embed)
+    import lyra.memory as memory
+    importlib.reload(memory)
+    import lyra.transcript as transcript
+    importlib.reload(transcript)
+    return memory, transcript
+
+
+def _seed(memory):
+    """A turn where Brian narrates a hand and Lyra logs it, then replies."""
+    memory.ensure_session("s1", name="Meadows 1/3")
+    memory.remember("s1", "user", "got it in with a set, he had the flush draw and bricked")
+    memory.add_tool_event("s1", "record_hand", {"result": "won", "pot": 750}, "hand #42 logged")
+    memory.add_tool_event("s1", "log_stack", {"amount": 750, "note": "doubled up"}, "ok")
+    memory.remember("s1", "assistant", "Clean stack-off — logged it to your timeline.")
+
+
+def test_tool_events_roundtrip_parses_args(mods):
+    memory, _ = mods
+    _seed(memory)
+    events = memory.tool_events("s1")
+    assert [e["tool"] for e in events] == ["record_hand", "log_stack"]
+    assert events[0]["args"] == {"result": "won", "pot": 750}   # parsed back to a dict
+    assert events[1]["result"] == "ok"
+
+
+def test_markdown_interleaves_speech_and_actions_in_order(mods):
+    memory, transcript = mods
+    _seed(memory)
+    md = transcript.as_markdown("s1", name="Meadows 1/3")
+    # user message, then both tool calls, then assistant reply — in that order
+    i_user = md.index("got it in with a set")
+    i_hand = md.index("record_hand")
+    i_stack = md.index("log_stack")
+    i_reply = md.index("Clean stack-off")
+    assert i_user < i_hand < i_stack < i_reply
+    assert "**Brian**" in md and "**Lyra**" in md
+    assert "⚙" in md
+
+
+def test_json_export_is_machine_readable(mods):
+    memory, transcript = mods
+    _seed(memory)
+    payload = transcript.as_json("s1", name="Meadows 1/3")
+    assert payload["session_id"] == "s1"
+    types = [e["type"] for e in payload["events"]]
+    assert types == ["message", "tool", "tool", "message"]
+    json.dumps(payload)  # must be serializable
+
+
+def test_build_returns_filename_and_media_type(mods):
+    memory, transcript = mods
+    _seed(memory)
+    body_md, mt_md, fn_md = transcript.build("s1", "md", "Meadows 1/3")
+    body_js, mt_js, fn_js = transcript.build("s1", "json", "Meadows 1/3")
+    assert fn_md.endswith(".md") and "markdown" in mt_md
+    assert fn_js.endswith(".json") and mt_js == "application/json"
+    assert body_md and body_js
+
+
+def test_delete_session_clears_tool_events(mods):
+    memory, _ = mods
+    _seed(memory)
+    memory.delete_session("s1")
+    assert memory.tool_events("s1") == []