fix(miner): same None-metadata guard for status() histogram loop

`status()` walks `col.get(include=["metadatas"])` and buckets each drawer
into a `wing_rooms[wing][room]` histogram. The same ChromaDB return shape
fixed in the search print path — `None` entries in the `metadatas` list
for drawers with no stored metadata — crashes the status command with:

    AttributeError: 'NoneType' object has no attribute 'get'

Applies the matching ``m = m or {}`` guard so None-metadata drawers roll
up under the existing `?/?` fallback bucket instead of killing the
command mid-tally. Reproduced on a 135K-drawer palace where two drawers
had `metadata=None`; both now show under `WING: ? / ROOM: ?` in the
tally while the command prints the full histogram as designed.

Adds a regression test that feeds `status()` a fake collection whose
`get()` returns a `None` in the middle of the metadatas list and asserts
both the fallback bucket and the real wing render.

Author: jphein

mempalace/miner.py

@@ -854,6 +854,7 @@ def status(palace_path: str):
 
     wing_rooms = defaultdict(lambda: defaultdict(int))
     for m in metas:
+        m = m or {}
         wing_rooms[m.get("wing", "?")][m.get("room", "?")] += 1
 
     print(f"\n{'=' * 55}")

tests/test_miner.py

@@ -343,6 +343,36 @@ def test_status_missing_palace_does_not_create_empty_collection(tmp_path, capsys
     assert not palace_path.exists()
 
 
+def test_status_handles_none_metadata_without_crash(tmp_path, capsys):
+    """status must not crash when col.get returns a None entry in metadatas.
+
+    Palaces can contain drawers whose metadata was never set (older mining
+    paths, drawers written by third-party tools). Before the guard, status
+    crashed mid-tally with ``AttributeError: 'NoneType' object has no
+    attribute 'get'`` at the wing/room histogram line."""
+    from unittest.mock import patch
+
+    class FakeCol:
+        def count(self):
+            return 2
+
+        def get(self, *args, **kwargs):
+            return {
+                "ids": ["a", "b"],
+                "documents": ["doc a", "doc b"],
+                "metadatas": [{"wing": "proj", "room": "r"}, None],
+            }
+
+    with patch("mempalace.miner.get_collection", return_value=FakeCol()):
+        status(str(tmp_path))
+
+    out = capsys.readouterr().out
+    # No crash; the None-metadata row is counted under the ?/? fallback
+    # alongside the real wing=proj row.
+    assert "WING: ?" in out
+    assert "WING: proj" in out
+
+
 # ── normalize_version schema gate ───────────────────────────────────────
 #
 # When the normalization pipeline changes shape (e.g., strip_noise lands),