fix: openings and markers keep their identity across a space switch (#525)

Lit reuses list nodes by position. The opening list and the device markers had
no keys, so on a space switch the leaf that held a slot kept its DOM node and
only changed values — and `.op-leaf` (transform) and `.op-arc`
(stroke-dashoffset) carry a 0.6 s transition, so the browser animated a door
that never moved: the new floor's leaf drove in from the previous floor's
opening angle. Measured on two spaces with a door in the same place and
opposite contact states: the node is reused, transform goes
`rotate(-90deg) → rotate(0deg)`, dash offset `0 → 125.66`, both transitions
`running`. The marker shell adds two more with its `box-shadow`.

Both lists are now rendered through `repeat(…, (item) => item.id, …)`, the
same lesson `glow-scene.ts` already learned for the Glow spots. The trap is
written where it starts — above the two transitions in `plan.styles.ts` —
because that is the file someone edits when adding the next animated property.
`houseplan-card.ts` is at its line ceiling, and the note would have cost the
budget a dozen lines for nothing: the swap itself is line-for-line.

The witness walks the shadow tree per element. `document.getAnimations()` is
empty here EVEN ON THE BROKEN CODE — the card lives in a shadow root and the
document-level call does not reach into it, and the issue proposed exactly
that call. The smoke also builds its own fixture: the demo home has no
openings at all, so two doors in two spaces are prepared in the smoke, and it
asserts the other half of the contract as well — a real contact change inside
one space still animates the leaf.

On `origin/dev` the smoke fails on five facts, naming the offenders:
`op-arc:stroke-dashoffset`, `op-leaf:transform`, `device-shell-frame:box-shadow`
twice. Mutants `openings-rendered-without-keys` and
`device-markers-rendered-without-keys` put each `map` back.

Perf, 7 samples against `19e421b3`: spaceSwitchMs 524.8 (limit 769.35, base
512.9), switchCycleMs 1293.9 (1696.28, 1256.5), firstStableRenderMs 2533.8
(3000, 2529.2), modelReadyMs 732.7 (944.97, 726.9), longTask.maxSingleMs 663
(910, 660) — `benchmark:compare` green in full.

The initial View graph grows 241 B gzip: `repeat` enters it for the first
time. The #438 ceiling is recentred 300 400 → 300 700 with the usual dated
note; measured 300 059 B keeps 641 B above and 1 359 B below the band. The
301 066 B budget is untouched, but only 366 B now separate the ceiling from
it — the #367 headroom debt has stopped being theoretical.

Issue: #525
User-Visible: yes

src/houseplan-card.ts

@@ -11784,7 +11784,7 @@ export class HouseplanCard extends LitElement {
               view,
               (point) => this._scenePoint(point),
             )}
-            ${devs.map((d) => this._renderDevice(
+            ${repeat(devs, (d) => d.id, (d) => this._renderDevice(
               d, view, showLqi, isoOverlays?.devices.get(d.id),
             ))}
             ${this._renderVacuums(this._renderVacuumDevices, view, space.id)}
@@ -12993,7 +12993,7 @@ export class HouseplanCard extends LitElement {
     const walls = this._spaceWalls;
     const openCuts = this._openCuts();
     const openingWallIndex = this._openingWallIndexFor(space, openCuts).value;
-    return svg`<g class="openinglayer">${items.map((o) => {
+    return svg`<g class="openinglayer">${repeat(items, (o) => o.id, (o) => {
       if (o.orphanReason) return svg`<g class="opening orphan" data-hp="opening-orphan"
         data-id=${o.id} role="button" tabindex="0"
         aria-label=${this._t('opening.partition_orphan')}

src/styles/plan.styles.ts

@@ -519,7 +519,18 @@ export const planStyles = css`
       stroke: var(--hp-accent);
       stroke-opacity: 1;
     }
-    /* doors, windows & gates */
+    /* doors, windows & gates
+
+       #525: these two transitions are the reason the opening list is rendered
+       with repeat(items, (o) => o.id, ...) and not a bare map(). Lit reuses
+       list nodes by POSITION, so on a space switch the leaf that held a slot
+       kept its DOM node and only changed values — and the browser dutifully
+       animated a door that never moved: the new floor's leaf drove in from the
+       previous floor's opening angle, 0.6 s of an event that did not happen.
+       Anything animated that is rendered from a list needs a key. The Glow
+       spots learned it first (glow-scene.ts, opacity), the openings and the
+       device markers (.device-shell-frame, box-shadow) with this issue.
+       Witness: demo/smoke_space_switch_transitions.mjs. */
     .op-leaf {
       transition: transform 0.6s ease;
     }