UX improvements: mobile bottom sheet, cuisine taxonomy, search enhancements

- Add BottomSheet component for Google Maps-style restaurant detail on mobile
  (3-snap drag: 40%/55%/92%, velocity-based close, backdrop overlay)
- Mobile map mode now full-screen with bottom sheet overlay for details
- Collapsible filter panel on mobile with active filter badge count
- Standardized cuisine taxonomy (46 categories: 한식|국밥, 일식|스시 etc.)
  with LLM remap endpoint and admin UI button
- Enhanced search: keyword search now includes foods_mentioned + video title
- Search results include channels array for frontend filtering
- Channel filter moved to frontend filteredRestaurants (not API-level)
- LLM extraction prompt updated for pipe-delimited region + cuisine taxonomy
- Vector rebuild endpoint with rich JSON chunks per restaurant
- Geolocation-based auto region selection on page load
- Desktop filters split into two clean rows

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/components/BottomSheet.tsx

@@ -0,0 +1,116 @@
+"use client";
+
+import { useCallback, useEffect, useRef, useState } from "react";
+
+interface BottomSheetProps {
+  open: boolean;
+  onClose: () => void;
+  children: React.ReactNode;
+}
+
+const SNAP_POINTS = { PEEK: 0.4, HALF: 0.55, FULL: 0.92 };
+const VELOCITY_THRESHOLD = 0.5;
+
+export default function BottomSheet({ open, onClose, children }: BottomSheetProps) {
+  const sheetRef = useRef<HTMLDivElement>(null);
+  const contentRef = useRef<HTMLDivElement>(null);
+  const [height, setHeight] = useState(SNAP_POINTS.PEEK);
+  const [dragging, setDragging] = useState(false);
+  const dragState = useRef({ startY: 0, startH: 0, lastY: 0, lastTime: 0 });
+
+  // Reset to peek when opened
+  useEffect(() => {
+    if (open) setHeight(SNAP_POINTS.PEEK);
+  }, [open]);
+
+  const snapTo = useCallback((h: number, velocity: number) => {
+    // If fast downward swipe, close
+    if (velocity > VELOCITY_THRESHOLD && h < SNAP_POINTS.HALF) {
+      onClose();
+      return;
+    }
+    // Snap to nearest point
+    const points = [SNAP_POINTS.PEEK, SNAP_POINTS.HALF, SNAP_POINTS.FULL];
+    let best = points[0];
+    let bestDist = Math.abs(h - best);
+    for (const p of points) {
+      const d = Math.abs(h - p);
+      if (d < bestDist) { best = p; bestDist = d; }
+    }
+    // If dragged below peek, close
+    if (h < SNAP_POINTS.PEEK * 0.6) {
+      onClose();
+      return;
+    }
+    setHeight(best);
+  }, [onClose]);
+
+  const onTouchStart = useCallback((e: React.TouchEvent) => {
+    // Don't intercept if scrolling inside content that has scrollable area
+    const content = contentRef.current;
+    if (content && content.scrollTop > 0 && height >= SNAP_POINTS.FULL - 0.05) return;
+
+    const y = e.touches[0].clientY;
+    dragState.current = { startY: y, startH: height, lastY: y, lastTime: Date.now() };
+    setDragging(true);
+  }, [height]);
+
+  const onTouchMove = useCallback((e: React.TouchEvent) => {
+    if (!dragging) return;
+    const y = e.touches[0].clientY;
+    const vh = window.innerHeight;
+    const deltaRatio = (dragState.current.startY - y) / vh;
+    const newH = Math.max(0.1, Math.min(SNAP_POINTS.FULL, dragState.current.startH + deltaRatio));
+    setHeight(newH);
+    dragState.current.lastY = y;
+    dragState.current.lastTime = Date.now();
+  }, [dragging]);
+
+  const onTouchEnd = useCallback(() => {
+    if (!dragging) return;
+    setDragging(false);
+    const dt = (Date.now() - dragState.current.lastTime) / 1000 || 0.1;
+    const dy = (dragState.current.startY - dragState.current.lastY) / window.innerHeight;
+    const velocity = -dy / dt; // positive = downward
+    snapTo(height, velocity);
+  }, [dragging, height, snapTo]);
+
+  if (!open) return null;
+
+  return (
+    <>
+      {/* Backdrop */}
+      <div
+        className="fixed inset-0 z-40 bg-black/20 md:hidden"
+        style={{ opacity: Math.min(1, (height - 0.2) * 2) }}
+        onClick={onClose}
+      />
+
+      {/* Sheet */}
+      <div
+        ref={sheetRef}
+        className="fixed bottom-0 left-0 right-0 z-50 md:hidden flex flex-col bg-white rounded-t-2xl shadow-2xl"
+        style={{
+          height: `${height * 100}vh`,
+          transition: dragging ? "none" : "height 0.3s cubic-bezier(0.2, 0, 0, 1)",
+        }}
+        onTouchStart={onTouchStart}
+        onTouchMove={onTouchMove}
+        onTouchEnd={onTouchEnd}
+      >
+        {/* Handle bar */}
+        <div className="flex justify-center pt-2 pb-1 shrink-0 cursor-grab">
+          <div className="w-10 h-1 bg-gray-300 rounded-full" />
+        </div>
+
+        {/* Content */}
+        <div
+          ref={contentRef}
+          className="flex-1 overflow-y-auto overscroll-contain"
+        >
+          {children}
+        </div>
+      </div>
+    </>
+  );
+}