Units get descriptions too — both levels of the furniture speak

Eric's correction: the opening-level description shipped, but the
unit deserved one as well (my own example sentence was unit-scale
prose). Units take a description at creation and edit it in place —
a linkish add/edit control under the unit's name with an inline
input — shown as quiet meta text on the card and stored in
furniture.json. Label addresses, zone matches, descriptions explain;
now at both scales.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016jXZFSTZQKzAC8fqpWSz9g

tests/test_shelves.py

@@ -820,3 +820,23 @@ def test_opening_descriptions_round_trip(tmp_path):
 
     saved = _json.loads(cfg.furniture_path.read_text())["units"][0]["openings"][0]
     assert saved["description"] == "tall bookcase by the window"
+
+
+def test_unit_descriptions_round_trip(tmp_path):
+    web, cfg = _web(tmp_path, {})
+    web.post(
+        "/api/furniture/add-unit",
+        json={"name": "Den", "description": "the wall behind the couch"},
+    )
+    assert (
+        web.get("/api/shelves").json()["units"][0]["description"]
+        == "the wall behind the couch"
+    )
+    web.post(
+        "/api/furniture/edit-unit",
+        json={"name": "Den", "description": "now in the study"},
+    )
+    import json as _json
+
+    saved = _json.loads(cfg.furniture_path.read_text())["units"][0]
+    assert saved["description"] == "now in the study"