Prepare v1.75.0-beta.1

Seven version sources move together to 1.75.0-beta.1, both changelogs
close their section over what has landed since the stable v1.74.0, the
release notes carry the one shipped bullet on each side with the grouped
small-fixes bullet last, and STATUS says what this beta is.

What the user gets: the House Plan sidebar page can no longer serve a
previous version of the card. The panel entry fetched it through
`./houseplan-card.js` — a relative specifier, and relative resolution
does not inherit the `?v=` a dashboard gets from its Lovelace resource,
while the entry files carry no Cache-Control at all. A browser was free
to answer from its own heuristic cache for hours, and a stale loader
named a stale immutable chunk, so the panel ran an old card against the
current backend with nothing but the version banner to show for it —
and reloading could not help, because the address never changed (#535).

Internal in the line: #536 — the version banner now asks the host to
repaint when it drops the notice on disconnect, instead of leaving its
removal to whatever unrelated update happened to run next.

npm test 2532/2530/0 fail (the #349 manifest-tracking check goes green
with this commit), release contract green on all seven sources, bundle
287 323 B gzip inside the ceiling, docs strict green.

The `Release:` trailer is what asks CI for the heavy gates — smokes,
golden and the full performance comparison — on this exact SHA (#479).

Issue: #535
User-Visible: yes
Release: v1.75.0-beta.1

src/houseplan-card.ts

@@ -417,7 +417,7 @@ import type { MarkerRoomReferenceSnapshot } from './room-reference-transaction';
 import { SummaryRuntimeSlot, summaryRuntimeLoader } from './summary-runtime-loader';
 import { displayVersion } from './card-version';
 
-const CARD_VERSION = '1.74.0';
+const CARD_VERSION = '1.75.0-beta.1';
 const ENTRY_BUILD_FINGERPRINT = '__HOUSEPLAN_SOURCE_FINGERPRINT__';
 const EDITOR_RETRY_ASSET = '__HOUSEPLAN_EDITOR_RETRY_ASSET__';
 const ISO_RETRY_ASSET = '__HOUSEPLAN_ISO_RETRY_ASSET__';

src/houseplan-editor-runtime.ts

@@ -388,7 +388,7 @@ import {
   rewriteMarkerRoomReferences, type MarkerRoomReferenceSnapshot,
 } from './room-reference-transaction';
 
-const CARD_VERSION = '1.74.0';
+const CARD_VERSION = '1.75.0-beta.1';
 
 // #474: the editor imports the furniture artwork statically and hands it to
 // the page runtime the moment this chunk evaluates — before the loader's