ux v1.30.2: editor tabs redesign

- two tabs only: 'Plan editor' / 'Device editor'; View is the implicit
  default state, no tab
- Device editor gets its own bottom toolbar (add/show-all/reset/rules
  moved from the header), mirroring the Plan toolbar
- X button on both toolbars and inside the active tab returns to View;
  re-click on active tab is a no-op; Plan<->Devices switches directly
- smoke_editor_tabs.mjs; TESTING/CHANGELOG/UX-MODES same-commit

docs/TESTING.md

@@ -140,6 +140,11 @@ Run the *core flows* (marked ★ below) in each environment at least once per mi
       (explicit ripple color still wins); off/white lights unchanged [auto]
 - [ ] Alarm pulse (v1.27.0): leak/smoke/gas/CO/siren in 'on' pulse a red ring over any
       display mode; clears on 'off'; unavailable never alarms [auto]; reduced-motion static
+- [ ] Editor tabs (v1.30.2): only two tabs — "Plan editor" / "Device editor"
+      (no View button; View is the default state); clicking a tab opens its
+      bottom toolbar (Devices got its own bar with add/show-all/reset/rules);
+      the bar and the active tab both show an X that returns to View; re-click
+      on the active tab does nothing; Plan↔Devices switches directly [auto]
 - [ ] Space gear (v1.30.1): the cog next to the space name is visible in every
       mode (admins only), vertically centered with the tab text; clicking it
       opens space settings without switching the tab; "+" tab stays Plan-only [auto]