fix: vision slot filters to image-capable + custom models (was relaxing for all providers)

The prior change made the vision slot show every model (image-capable first),
which relaxed the filter for built-in providers too — built-in text-only models
became selectable for Vision. Centralize the vision rule in ModelMenuList:
built-ins must report image input; custom-endpoint models stay selectable (their
capability may be unreported). Image-capable still float first.

components/settings/agent-section.tsx

@@ -600,10 +600,6 @@ export function AgentSection({
 					const chosen = coord ? catalog?.find((m) => m.id === coord.id && m.provider === coord.provider) : undefined;
 					const levels = chosen ? chosen.supportedLevels : THINKING_LEVELS;
 					const thisMenuOpen = openMenu?.target === slot ? openMenu.kind : null;
-					// Vision slot: image-capable models float first, but all stay
-					// selectable (a custom endpoint that doesn't report modality must
-					// remain pickable) — so this orders, never filters.
-					const slotCatalog = catalog;
 					return (
 						<SettingsRow
 							key={slot}
@@ -648,10 +644,10 @@ export function AgentSection({
 										menuClass="flex w-[22rem] flex-col rounded-xl border border-border bg-card p-2 text-xs shadow-xl"
 									>
 										<ModelMenuList
-											models={slotCatalog ?? undefined}
+											models={catalog ?? undefined}
 											effectiveId={modelId}
 											effectiveProvider={provider}
-											prioritizeImage={slot === "vision"}
+											vision={slot === "vision"}
 											onPick={(entry) => {
 												// Auto-populate (chunk 2, owner: "populate everywhere"): the
 												// fresh pick writes a level — the stored one rides as-is