fix(2.5d): room metrics keep their distance from the name at every zoom (#665)

The raised room label in 2.5D View sized its own box to the 44 px touch
minimum (min-height + justify-content: center). The name therefore sat
centred in 44 px while the metrics row, placed absolutely from the label
bottom, hung (44 - name height) / 2 below it: 18.3 px at a 9 px name and
6.4 px at a 39 px one on the demo stand, against a constant 0.1 name
height on the flat plan.

The 44 x 44 px floor moves into an invisible ::before (the door-lock
pattern), z-index -1 inside the label stacking context; the label box is
sized by its text again.

demo/smoke_iso_room_label_metrics.mjs measures gap / name height at two
cameras (font x4) in Flat and 2.5D, and the 44 px floor and area-link hit
targets on labels no raised device covers. Mutant
iso-room-label-44-box-centres-name.

Screenshots: 11 frames pixel-identical, fingerprint only.

Issue: #665
User-Visible: yes

scripts/mutation-registry.mjs

@@ -3391,6 +3391,16 @@ const MUTANT_DEFINITIONS = [
       replace: "",
     }],
   },
+  {
+    id: 'iso-room-label-44-box-centres-name',
+    guard: 'node demo/smoke_iso_room_label_metrics.mjs',
+    because: '#665: sizing the raised label box to 44 px centres the name in it and pushes the metrics row away by (44 - name) / 2, so the gap drifts with zoom',
+    patches: [{
+      file: 'src/styles/plan.styles.ts',
+      find: "    .stage.projection-iso.mode-view .roomlabel {\n      box-sizing: border-box;\n",
+      replace: "    .stage.projection-iso.mode-view .roomlabel {\n      box-sizing: border-box;\n      min-height: 44px;\n      justify-content: center;\n",
+    }],
+  },
   {
     id: 'static-card-descendants-hit-testable',
     guard: 'node demo/smoke_space_card.mjs',