v1.50.1: the v1.50.0 review (HP-1500-01..03)

- HP-1500-02: the stage budget was the absolute document coordinate, so any
  tall dashboard content before the card was billed as header and the stage
  collapsed to 0px. Measure our own chrome relative to the card plus a
  bounded (<=120px) allowance for what the viewport keeps above us; re-measure
  on window resize, remove the listener in disconnectedCallback.
- HP-1500-03, both layers: contentBounds opens a near-zero axis (< ~an icon)
  up to a 200-unit floor and ignores extra points outside a canvas envelope
  (-25%..125%) for FRAMING purposes only; the server bounds layout coordinates
  to +-4 — any finite float used to pass, and one 1e100 hid the plan from
  every viewer. A thin real room keeps its tight frame; the gate sensor past
  the edge still stretches it.
- HP-1500-01: no automatic double-transform — a correct layout and a stranded
  one are indistinguishable, and guessing wrong corrupts good data. Explicit
  admin command houseplan/geometry/repair: dry_run previews, the backup rides
  the same store write, undo restores, and routine layout writes now preserve
  unrelated store keys instead of eating the backup.

Tests: contentBounds guards (unit), layout coordinate bounds + repair
lifecycle (harness), card-below-content smoke. Inventory: 139 / 49 / 42 / 64.

demo/smoke_zoom_out.mjs

@@ -61,4 +61,21 @@ out.devicesStretchFrame = await page.evaluate(() => {
   return after[0] + after[2] > before[0] + before[2] + 20; // right edge follows the lamp
 });
 
+// -- a card BELOW other dashboard content still gets a stage (HP-1500-02) --
+out.stageSurvivesContentAbove = await page.evaluate(async () => {
+  const spacer = document.createElement('div');
+  spacer.style.height = '900px';
+  document.body.insertBefore(spacer, document.body.firstChild);
+  window.dispatchEvent(new Event('resize'));
+  await new Promise((r) => setTimeout(r, 120));
+  const c = window.__card;
+  const sr = c.shadowRoot || c.renderRoot;
+  const h = sr.querySelector('.stage').getBoundingClientRect().height;
+  spacer.remove();
+  window.dispatchEvent(new Event('resize'));
+  await new Promise((r) => setTimeout(r, 120));
+  // the old code billed the 900px spacer as "header" and left a 0px stage
+  return h > 300;
+});
+
 await finish(browser, checkAll(out));