fix(desktop): preserve other providers' hide-all in model visibility dialog

#43496 added a per-provider hide-all sentinel ('provider::') so emptying a provider in the Edit Models dialog stopped re-expanding its defaults. That fixed the single-provider case, but the dialog's toggle handler seeds its working set from effectiveVisibleKeys(), which strips ALL sentinels before returning. So persisting after any toggle silently dropped every OTHER provider's hide-all sentinel; those providers then looked 'never customized' and re-enabled all their models on the next render.

Split resolution into two functions:

- resolveVisibleKeys(): stored keys + curated default expansion, with hide-all sentinels PRESERVED — the canonical working set the toggle handler mutates and persists.

- effectiveVisibleKeys(): resolveVisibleKeys() then strips sentinels, for display only (unchanged contract).

Move the toggle set-computation into a pure, unit-tested toggleModelVisibility() that seeds from resolveVisibleKeys(), so sibling sentinels survive the persist. Add regression tests that drive the real toggle handler across multiple providers.

Follow-up to #43496; completes the fix for #43485 (cross-provider case).

apps/desktop/src/components/model-visibility-dialog.tsx

@@ -14,10 +14,9 @@ import {
   $visibleModels,
   collapseModelFamilies,
   effectiveVisibleKeys,
-  emptyProviderSentinelKey,
-  isProviderSentinel,
   modelVisibilityKey,
-  setVisibleModels
+  setVisibleModels,
+  toggleModelVisibility
 } from '@/store/model-visibility'
 import type { ModelOptionProvider, ModelOptionsResponse } from '@/types/hermes'
 
@@ -61,25 +60,7 @@ export function ModelVisibilityDialog({
   const visible = effectiveVisibleKeys(stored, providers)
 
   const toggle = (provider: ModelOptionProvider, model: string) => {
-    const next = new Set(effectiveVisibleKeys($visibleModels.get(), providers))
-    const key = modelVisibilityKey(provider.slug, model)
-    const sentinel = emptyProviderSentinelKey(provider.slug)
-
-    if (next.has(key)) {
-      next.delete(key)
-
-      // Check if this was the last real model for this provider.
-      const remainingForProvider = [...next].some(k => k.startsWith(`${provider.slug}::`) && !isProviderSentinel(k))
-
-      if (!remainingForProvider) {
-        next.add(sentinel)
-      }
-    } else {
-      next.delete(sentinel)
-      next.add(key)
-    }
-
-    setVisibleModels(next)
+    setVisibleModels(toggleModelVisibility($visibleModels.get(), providers, provider.slug, model))
   }
 
   const q = search.trim().toLowerCase()