v1.51.0: explicit hide flags, the yellow principle, phone editor gestures, room button

The dev batch since v1.50.4, released as one:
- hiding is a per-device checkbox seeded once from the old filter
  (docs/FILTERING.md); blue ghosts under a local 'Show hidden' toggle
- yellow = doing its main job now; TRVs glow by hvac_action, service
  switches can no longer become a device's primary
- pinch/pan gestures in every editor on touch
- the room settings button: visual centre (inscribed circle + centroid
  pull), icon-derived size, zooms with the plan; metrics visible in the
  plan editor

Inventory: 147 frontend / 51 pure / 43 harness / 68 smokes.

custom_components/houseplan/manifest.json

@@ -16,5 +16,5 @@
   "issue_tracker": "https://github.com/Matysh/houseplan-card/issues",
   "requirements": [],
   "single_config_entry": true,
-  "version": "1.50.4"
+  "version": "1.51.0"
 }