docs: Update pagination navigation documentation and remove obsolete components

- Deleted the outdated `PageGroupNav` component and its related documentation.
- Introduced a new document for the direct input navigation feature in pagination, detailing the rationale for the change and the new user experience.
- Updated the checklist to reflect the completion of the new pagination input feature and its implementation steps.

These changes enhance the clarity and usability of the pagination system in the project.

frontend/components/common/PageGroupNav.tsx

@@ -1,109 +0,0 @@
-"use client";
-
-import { ChevronLeft, ChevronRight, ChevronsLeft, ChevronsRight } from "lucide-react";
-import { Button } from "@/components/ui/button";
-import { cn } from "@/lib/utils";
-
-const DEFAULT_GROUP_SIZE = 10;
-
-interface PageGroupNavProps {
-  currentPage: number;
-  totalPages: number;
-  onPageChange: (page: number) => void;
-  disabled?: boolean;
-  groupSize?: number;
-}
-
-export function PageGroupNav({
-  currentPage,
-  totalPages,
-  onPageChange,
-  disabled = false,
-  groupSize = DEFAULT_GROUP_SIZE,
-}: PageGroupNavProps) {
-  const safeTotal = Math.max(1, totalPages);
-  const currentGroupIndex = Math.floor((currentPage - 1) / groupSize);
-  const groupStartPage = currentGroupIndex * groupSize + 1;
-
-  const lastGroupIndex = Math.floor((safeTotal - 1) / groupSize);
-  const lastGroupStartPage = lastGroupIndex * groupSize + 1;
-
-  const isFirstGroup = currentGroupIndex === 0;
-  const isLastGroup = currentGroupIndex === lastGroupIndex;
-
-  const slots: (number | null)[] = [];
-  for (let i = 0; i < groupSize; i++) {
-    const page = groupStartPage + i;
-    slots.push(page <= safeTotal ? page : null);
-  }
-
-  return (
-    <div className="flex items-center gap-1">
-      {/* << 첫 단락 */}
-      <Button
-        variant="outline"
-        size="sm"
-        onClick={() => onPageChange(1)}
-        disabled={isFirstGroup || disabled}
-        className="h-8 w-8 p-0 sm:h-9 sm:w-9"
-      >
-        <ChevronsLeft className="h-3 w-3 sm:h-4 sm:w-4" />
-      </Button>
-
-      {/* < 이전 단락 */}
-      <Button
-        variant="outline"
-        size="sm"
-        onClick={() => onPageChange((currentGroupIndex - 1) * groupSize + 1)}
-        disabled={isFirstGroup || disabled}
-        className="h-8 w-8 p-0 sm:h-9 sm:w-9"
-      >
-        <ChevronLeft className="h-3 w-3 sm:h-4 sm:w-4" />
-      </Button>
-
-      {/* 페이지 번호 (고정 슬롯) */}
-      {slots.map((page, idx) =>
-        page !== null ? (
-          <Button
-            key={idx}
-            size="sm"
-            variant={page === currentPage ? "default" : "outline"}
-            onClick={() => onPageChange(page)}
-            disabled={disabled}
-            className={cn(
-              "h-8 w-8 p-0 text-xs sm:h-9 sm:w-9 sm:text-sm",
-              page === currentPage &&
-                "font-bold ring-2 ring-primary ring-offset-1 ring-offset-background",
-            )}
-          >
-            {page}
-          </Button>
-        ) : (
-          <div key={idx} className="h-8 w-8 cursor-default sm:h-9 sm:w-9" />
-        ),
-      )}
-
-      {/* > 다음 단락 */}
-      <Button
-        variant="outline"
-        size="sm"
-        onClick={() => onPageChange((currentGroupIndex + 1) * groupSize + 1)}
-        disabled={isLastGroup || disabled}
-        className="h-8 w-8 p-0 sm:h-9 sm:w-9"
-      >
-        <ChevronRight className="h-3 w-3 sm:h-4 sm:w-4" />
-      </Button>
-
-      {/* >> 마지막 단락 */}
-      <Button
-        variant="outline"
-        size="sm"
-        onClick={() => onPageChange(lastGroupStartPage)}
-        disabled={isLastGroup || disabled}
-        className="h-8 w-8 p-0 sm:h-9 sm:w-9"
-      >
-        <ChevronsRight className="h-3 w-3 sm:h-4 sm:w-4" />
-      </Button>
-    </div>
-  );
-}