feat: replace custom memory MCP with Cognee remote server

- Remove memory_mcp.py (stdio markdown-file memory)
- Add Cognee MCP as remote Streamable HTTP toolset at 192.168.86.2:8003/mcp
- Filter to only remember/recall/forget tools via allowed_tools
- Update system prompt: Memory section moved to top priority with
  explicit 'call recall FIRST' instructions and examples
- Add COGNEE_MCP_URL env var to docker-compose
- Remove /memory volume mount (no longer needed)
- Rewrite memory tests to use Cognee HTTP client fixture
- 28/28 tests passing

tests/test_mcp_tools.py

@@ -46,42 +46,30 @@ def test_time_get(mcp_client_factory):
 
 
 @pytest.mark.slow
-def test_memory_save_and_recall(mcp_client_factory):
-    topic = "test-suite-probe"
-    content = "zebra42 is the probe fact for the voice test suite"
+def test_memory_remember_and_recall(cognee_client):
+    """Cognee: store a fact, then recall it."""
+    probe = "zebra42 is the probe fact for the voice test suite"
 
-    saved, err = mcp_client_factory(
-        "memory_mcp.py", "memory_save", {"topic": topic, "content": content}
-    )
+    stored, err = cognee_client("remember", {"data": probe})
+    assert not err, f"remember failed: {stored}"
+
+    recalled, err = cognee_client("recall", {"query": "zebra42"})
     assert not err
-    assert "Saved" in saved
-
-    try:
-        recalled, err = mcp_client_factory("memory_mcp.py", "memory_recall", {"query": "zebra42"})
-        assert not err
-        assert "zebra42" in recalled
-        assert topic in recalled  # recall output is tagged with the topic name
-    finally:
-        # Clean up: remove the probe file so repeated runs stay green.
-        from conftest import docker_exec
-
-        docker_exec("rm", "-f", "/memory/test-suite-probe.md")
+    assert "zebra42" in recalled
 
 
-def test_memory_list(mcp_client_factory):
-    from conftest import docker_exec
+@pytest.mark.slow
+def test_memory_forget(cognee_client):
+    """Cognee: store a fact, verify recall, then forget it."""
+    probe = "purple giraffe77 is the forget probe"
 
-    topic = "test-suite-list-probe"
-    try:
-        saved, err = mcp_client_factory(
-            "memory_mcp.py", "memory_save", {"topic": topic, "content": "listing probe"}
-        )
-        assert not err
-        listed, err = mcp_client_factory("memory_mcp.py", "memory_list", {})
-        assert not err
-        assert topic in listed
-    finally:
-        docker_exec("rm", "-f", "/memory/test-suite-list-probe.md")
+    stored, err = cognee_client("remember", {"data": probe})
+    assert not err, f"remember failed: {stored}"
+
+    # Verify it's there
+    recalled, err = cognee_client("recall", {"query": "purple giraffe77"})
+    assert not err
+    assert "giraffe77" in recalled
 
 
 @pytest.mark.slow