fix: standardize locked-vs-hidden treatment across all 9 per-tier gated features (v0.79.0)

Rule, applied consistently everywhere via a new isFeatureAvailableAnyTier() helper: if a feature is enabled on at least one tier, it stays visible for locked-out viewers with a small "Pro" badge and opens an upgrade prompt on click; if a feature is disabled on every tier, it hides entirely, since there's no upgrade path to point at.

Covers: recipe variations, meal/drink pairings, nutrition estimation, Markdown export (5 call sites), weekly nutrition, import from URL, import from photo, and the Instacart grocery-delivery menu item. Previously inconsistent — some hid outright, one showed a lock icon overlapping its own icon.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/web/app/(app)/collections/[id]/page.tsx

@@ -18,7 +18,7 @@ import { buttonVariants } from "@/components/ui/button";
 import { Tooltip, TooltipContent, TooltipProvider, TooltipTrigger } from "@/components/ui/tooltip";
 import { cn } from "@/lib/utils";
 import { ExportMarkdownButton } from "@/components/shared/export-markdown-button";
-import { getFeatureFlagMatrix, type Tier } from "@/lib/feature-flags";
+import { getFeatureFlagMatrix, isFeatureAvailableAnyTier, type Tier } from "@/lib/feature-flags";
 import { EmptyState } from "@/components/shared/empty-state";
 import { collectionToMarkdown } from "@/lib/markdown/collection";
 import { getMessages } from "@/lib/i18n/server";
@@ -33,7 +33,9 @@ export default async function CollectionPage({ params }: Params) {
   if (!session) return null;
   const m = getMessages((session.user as { locale?: string }).locale);
   const viewerTier = (session.user as { tier?: string }).tier as Tier | undefined ?? "free";
-  const canExportMarkdown = (await getFeatureFlagMatrix()).markdown_export[viewerTier];
+  const featureFlags = await getFeatureFlagMatrix();
+  const markdownExportLocked = !featureFlags.markdown_export[viewerTier];
+  const markdownExportAvailable = isFeatureAvailableAnyTier(featureFlags, "markdown_export");
 
   const col = await db.query.collections.findFirst({
     where: and(eq(collections.id, id), collectionVisibleToViewer(session.user.id)),
@@ -85,13 +87,14 @@ export default async function CollectionPage({ params }: Params) {
                   } />
                   <TooltipContent>{m.collections.exportPdf}</TooltipContent>
                 </Tooltip>
-                {canExportMarkdown && <ExportMarkdownButton
+                {markdownExportAvailable && <ExportMarkdownButton
                   markdown={collectionToMarkdown({
                     name: col.name,
                     description: col.description,
                     recipes: recipeList,
                   })}
                   filename={col.name}
+                  locked={markdownExportLocked}
                 />}
               </>
             )}