fix: recipe version diff readability + i18n, tooltip on markdown export

- Version compare used positional (index-by-index) list alignment —
  inserting one ingredient in the middle shifted every subsequent line
  out of alignment, making the whole rest of the list look changed.
  Switch to diffArrays (LCS-based) so insertions/deletions are
  detected properly; adjacent removed+added chunks still get paired
  for word-level diffing so a single edited item doesn't render as a
  full delete+insert.
- Translated "Title"/"Description"/"Ingredients"/"Steps" diff section
  headers, "Version History" sheet title, compare/restore buttons,
  loading/empty states, and the version-detail ingredient/step count
  summary (with proper plural forms).
- formatDate() in version history was hardcoded to "en-US" regardless
  of the app's locale — now uses the session locale.
- ExportMarkdownButton had no hover tooltip (bare title attribute) —
  wrap it in the same Tooltip pattern every other icon button in the
  toolbar uses.

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

apps/web/components/shared/export-markdown-button.tsx

@@ -10,6 +10,7 @@ import {
   DropdownMenuItem,
   DropdownMenuTrigger,
 } from "@/components/ui/dropdown-menu";
+import { Tooltip, TooltipContent, TooltipProvider, TooltipTrigger } from "@/components/ui/tooltip";
 
 export function ExportMarkdownButton({
   markdown,
@@ -43,11 +44,18 @@ export function ExportMarkdownButton({
 
   return (
     <DropdownMenu>
-      <DropdownMenuTrigger render={
-        <Button variant="ghost" size="icon" title={t("exportMarkdown")}>
-          <FileDown className="h-4 w-4" />
-        </Button>
-      } />
+      <TooltipProvider>
+        <Tooltip>
+          <TooltipTrigger render={
+            <DropdownMenuTrigger render={
+              <Button variant="ghost" size="icon">
+                <FileDown className="h-4 w-4" />
+              </Button>
+            } />
+          } />
+          <TooltipContent>{t("exportMarkdown")}</TooltipContent>
+        </Tooltip>
+      </TooltipProvider>
       <DropdownMenuContent align="end">
         <DropdownMenuItem onClick={() => { void handleCopy(); }}>
           <Copy className="h-4 w-4" />