Scripted demo-stand vacuum: the checklist needs a robot no hardware can provide

The public stand cannot run any Tier-A map integration (no radios, no
robots), which left the whole vacuum section of docs/TESTING.md untestable
outside the owner's home. demo_robot fakes exactly the surface the card
consumes: a Tasshack-shaped map sensor (dict vacuum_position, rooms named
after the plan rooms so auto-calibration has something to match, flipped Y
so the mirror default is meaningful) and a vacuum that drives a serpentine
route through every room in ~3.5 minutes and docks itself.

demo/stand/demo_robot/manifest.json

@@ -0,0 +1,10 @@
+{
+  "domain": "demo_robot",
+  "name": "Demo Robot Vacuum",
+  "codeowners": [],
+  "dependencies": [],
+  "documentation": "https://github.com/Matysh/houseplan-card/tree/dev/demo/stand/demo_robot",
+  "iot_class": "calculated",
+  "requirements": [],
+  "version": "1.0.0"
+}