Let the panel reach the card by its hashed name, not by the one address without a version

The sidebar page could serve a previous card for hours. It imported the
card through the stable facade, `./houseplan-card.js` — a relative
specifier, and relative resolution does not inherit a query. A dashboard
reaches the same file as `houseplan-card.js?v=1.74.0`, so an upgrade
changes its URL and the browser must refetch. The panel always asked for
the same address, and entries are served with no Cache-Control at all —
only ETag and Last-Modified — so the browser applies heuristic freshness
and may answer from cache without asking. A stale 1164-byte loader names
a stale chunk, chunks are immutable for a year, and the panel then ran a
previous card against the current backend without a single error. The
version banner was telling the truth; reloading could not help, because
the address never changed.

Rollup already emits the right edge: the panel's side-effect import
points straight at the shared implementation. The rewrite in
entryFallbackPlugin replaced it with the facade for a fallback that the
hashed name gives anyway — and better: a chunk the manifest no longer
serves now raises the panel's own "House Plan was updated" notice
instead of silently working on old code.

Two #486 assertions change meaning and are rewritten, not adjusted: the
panel no longer routes through the facade, and its initial graph no
longer contains it. The invariant they defended — the panel reuses the
exact card graph, never a second copy — is now stated over the
implementation, and a new test pins that no built entry reaches the card
by an address without a version.

Issue: #535
User-Visible: yes

test/houseplan-zip.test.mjs

@@ -42,7 +42,7 @@ test('#486 HACS zip contains both entries and rejects stale managed roots', () =
       gzipBytes: path === 'houseplan-card.js' ? 5 : path === 'houseplan-panel.js' ? 3 : 7,
       isEntry: path === 'houseplan-card.js' || path === 'houseplan-panel.js',
       imports: path === 'houseplan-panel.js'
-        ? ['houseplan-card.js']
+        ? ['houseplan-assets/card-HASH.js']
         : path === 'houseplan-card.js' ? ['houseplan-assets/card-HASH.js'] : [],
       dynamicImports: [],
     }));
@@ -54,9 +54,9 @@ test('#486 HACS zip contains both entries and rejects stale managed roots', () =
       initialViewFiles: ['houseplan-assets/card-HASH.js', 'houseplan-card.js'],
       initialViewGzipBytes: 12,
       initialPanelFiles: [
-        'houseplan-assets/card-HASH.js', 'houseplan-card.js', 'houseplan-panel.js',
+        'houseplan-assets/card-HASH.js', 'houseplan-panel.js',
       ],
-      initialPanelGzipBytes: 15,
+      initialPanelGzipBytes: 10,
       initialPanelOnlyFiles: ['houseplan-panel.js'],
       initialPanelOnlyGzipBytes: 3,
       files,