test(mcp): add smoke-test args for ensure_kb + ground_paper

PR #28 added the ensure_kb and ground_paper MCP tools but did not add
their required-argument fixtures to _TOOL_ARGS, so test_tool_inventory
invoked them with no args and raised TypeError, failing CI. Add the
missing entries using the existing fake-DOI convention.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: lfnothias

tests/integration/test_mcp_smoke.py

@@ -299,6 +299,13 @@ def mock_state():
         "query": "CRISPR off-target effects",
     },
     "get_usage_guide": {},
+    "ensure_kb": {
+        "doi": "10.1234/fake-smoke-doi",
+    },
+    "ground_paper": {
+        "doi": "10.1234/fake-smoke-doi",
+        "question": "What is the reported yield?",
+    },
 }
 
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