Move UI to BoardUI with slate + salmon theme; add PDF plan export

- Adopt BoardUI (Pro init): theme tokens, Inter, .dark mode, Button,
  SegmentedControl, Meter, Skeleton and ThemeToggle; remap the app's
  color aliases onto BoardUI tokens and swap lucide for Remix icons
- Retint BoardUI's neutral ramp to cool slate with a salmon accent;
  drop the dotted background; raise muted text contrast
- Simplify the landing page and remove the overlap explorer
- Planner: explicit "I have this" toggle on grocery lines, pantry panel
  above the menu with the staples list spelled out, sticky aisle
  header fix, and a "Download PDF" plan export (jsPDF, lazy-loaded)
- Recipes: replace the family cabbage soup with Cade's Cabbage Soup
  (adds Bone-In Ham Steak to the catalog); remove Ham, Bean & Cabbage Soup
- Remove unused BoardUI components, dependencies and exports

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

utils/directional-icon.ts

@@ -0,0 +1,18 @@
+import {
+  RiArrowLeftLine,
+  RiArrowLeftSLine,
+  RiArrowRightLine,
+  RiArrowRightSLine,
+  RiSidebarFoldLine,
+  RiSidebarUnfoldLine,
+} from "@remixicon/react";
+
+/** Navigation glyphs mirror; logos, media controls and trend arrows do not. */
+const directionalIcons: ReadonlySet<unknown> = new Set([
+  RiArrowLeftLine, RiArrowLeftSLine, RiArrowRightLine, RiArrowRightSLine,
+  RiSidebarFoldLine, RiSidebarUnfoldLine,
+]);
+
+export function directionalIconClass(icon: unknown): string | undefined {
+  return directionalIcons.has(icon) ? "rtl:rotate-180" : undefined;
+}