fix(studio): persist canvas z-order actions correctly for static elements

An adversarial review of the canvas context-menu z-order pipeline (Bring to
Front / Forward / Backward / Send to Back) found the resolver math sound but
the glue between the menu and the commit hook broken:

- The menu optimistically wrote style.zIndex AND position: relative to the
  live elements BEFORE the commit hook ran. The hook decides whether to
  persist position by checking getComputedStyle(el).position === 'static' —
  always false after the pre-apply — so the position patch was never
  persisted on the menu path and the reorder silently reverted at the
  post-commit reload for any nested/static element (root clips survive only
  because the runtime forces position:absolute). The same pre-apply made the
  failure rollback capture the already-mutated values, restoring the broken
  state on persist errors. The menu no longer pre-applies; the hook owns the
  live writes (it already applied both synchronously) and now sees true
  priors. Siblings without a persistable identity still get their z applied
  live-only so a renumber stays visually coherent.
- The commit hook's entry.key store-sync plumbing had zero production
  callers; the store zIndex went stale until full reload. All three callers
  (canvas menu via PreviewOverlays, timeline lane z-sync, LayersPanel) now
  derive and pass the timeline store key (new deriveTimelineStoreKey helper).
- patchElementBatch discarded the server's per-patch matched[]; unresolvable
  siblings persisted partially and silently. Unmatched targets now warn and
  report save-failure telemetry (z-reorder-unmatched) without rolling back
  the matched subset.
- template/noscript elements counted as painting siblings, so renumber
  fallbacks wrote z-index/position into <template> tags in the source file.
  Excluded from the sibling family.
- The default undo coalesce key merged DISTINCT z actions within 300ms into
  one undo entry; the action kind is now part of the key (LayersPanel drags
  keep coalescing within a drag; explicit lane-move gesture keys untouched).
- rectsIntersect comment claimed touching rects intersect; the strict
  inequalities say otherwise — comment fixed.

packages/studio/src/components/editor/canvasContextMenuZOrder.ts

@@ -81,8 +81,18 @@ function isElementNode(node: Node): node is HTMLElement {
  * z-index onto the qa-clean audio element, and counting it as a sibling skews the
  * renumber for the visible elements. `<script>/<style>/<link>/<meta>` are also
  * non-painting and could otherwise pad the family / eat a z slot.
+ * `<template>/<noscript>` never paint either — letting them in meant renumber
+ * fallbacks wrote z-index/position into template source markup.
  */
-const NON_PAINTING_TAGS = new Set(["AUDIO", "SCRIPT", "STYLE", "LINK", "META"]);
+const NON_PAINTING_TAGS = new Set([
+  "AUDIO",
+  "SCRIPT",
+  "STYLE",
+  "LINK",
+  "META",
+  "TEMPLATE",
+  "NOSCRIPT",
+]);
 
 /** A painting element: an element node whose tag actually renders pixels. */
 function isPaintingElement(node: Node): node is HTMLElement {
@@ -112,7 +122,7 @@ function getFamily(target: HTMLElement): { entries: RenderEntry[]; targetIndex:
   return { entries, targetIndex };
 }
 
-/** True if two DOM bounding rects intersect (even if touching). */
+/** True if two DOM bounding rects strictly overlap (rects that merely touch do NOT intersect). */
 function rectsIntersect(
   a: { left: number; top: number; right: number; bottom: number },
   b: { left: number; top: number; right: number; bottom: number },