Shell shortcuts: /, D, [ ], Ctrl+K palette + neighbors endpoint

Backend:
- GET /api/files/{md5}/neighbors/ returns previous/next items in the
  current ordering (name, size, created_at) for keyboard navigation

Frontend:
- / focuses the library search input
- D downloads the file on the detail page
- [ and ] navigate to the previous/next item; hint shown on the page
- Ctrl/Cmd+K opens a command palette (navigation, toggle filters,
  focus search, log in/out); Escape closes it
- Sort order now persists alongside the other library filters so
  prev/next stays consistent

frontend/src/features/library/FileDetailPage.tsx

@@ -1,13 +1,15 @@
 import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
 import { ArrowLeft, Download } from "lucide-react";
-import { useState } from "react";
-import { Link, useParams } from "react-router-dom";
+import { useEffect, useState } from "react";
+import { Link, useNavigate, useParams } from "react-router-dom";
 
 import { Button, EmptyState, Spinner, inputClass } from "@/components/ui";
 import { api, errorMessage } from "@/lib/api";
 import { cn } from "@/lib/cn";
+import { isTypingTarget } from "@/lib/dom";
 import { formatBytes, formatDate } from "@/lib/format";
-import type { MediaItem, Rating } from "@/lib/types";
+import { useUi } from "@/store/ui";
+import type { FileNeighbors, MediaItem, Rating } from "@/lib/types";
 
 const ratingChoices: { value: Rating; label: string; active: string }[] = [
   {
@@ -114,12 +116,45 @@ function CustomDataCard({ item }: { item: MediaItem }) {
 
 export default function FileDetailPage() {
   const { md5 = "" } = useParams();
+  const navigate = useNavigate();
+  const ordering = useUi((state) => state.ordering);
+  const rawUrl = `/api/files/${md5}/raw/`;
+
   const query = useQuery({
     queryKey: ["file", md5],
     queryFn: () => api<MediaItem>(`/api/files/${md5}/`),
     enabled: md5.length > 0,
   });
 
+  const neighborsQuery = useQuery({
+    queryKey: ["neighbors", md5, ordering],
+    queryFn: () =>
+      api<FileNeighbors>(
+        `/api/files/${md5}/neighbors/?ordering=${encodeURIComponent(ordering)}`,
+      ),
+    enabled: md5.length > 0,
+  });
+
+  useEffect(() => {
+    function handleKeyDown(event: KeyboardEvent) {
+      if (event.ctrlKey || event.metaKey || event.altKey) return;
+      if (isTypingTarget(event.target)) return;
+      if (event.key === "d" || event.key === "D") {
+        event.preventDefault();
+        window.location.href = `${rawUrl}?download=1`;
+        return;
+      }
+      const neighbors = neighborsQuery.data;
+      if (event.key === "[" && neighbors?.previous) {
+        navigate(`/view/${neighbors.previous.md5}`);
+      } else if (event.key === "]" && neighbors?.next) {
+        navigate(`/view/${neighbors.next.md5}`);
+      }
+    }
+    window.addEventListener("keydown", handleKeyDown);
+    return () => window.removeEventListener("keydown", handleKeyDown);
+  }, [neighborsQuery.data, navigate, rawUrl]);
+
   if (query.isPending) {
     return (
       <div className="flex justify-center py-24">
@@ -142,7 +177,6 @@ export default function FileDetailPage() {
   }
 
   const item = query.data;
-  const rawUrl = `/api/files/${item.md5}/raw/`;
 
   return (
     <div className="flex flex-col gap-4">
@@ -211,6 +245,9 @@ export default function FileDetailPage() {
             >
               <Download className="h-4 w-4" /> Download
             </a>
+            <p className="mt-3 font-mono text-[11px] text-ctp-overlay0">
+              [ ] navigate · D download
+            </p>
           </section>
 
           <CustomDataCard key={item.updated_at} item={item} />

frontend/src/features/library/LibraryPage.tsx

@@ -1,11 +1,12 @@
 import { useQuery } from "@tanstack/react-query";
 import { Search, X } from "lucide-react";
-import { useState, type FormEvent } from "react";
+import { useState, useEffect, type FormEvent } from "react";
 
 import { MediaCard } from "@/components/MediaCard";
 import { Button, EmptyState, Spinner, inputClass } from "@/components/ui";
 import { api } from "@/lib/api";
 import { cn } from "@/lib/cn";
+import { isTypingTarget } from "@/lib/dom";
 import { useUi } from "@/store/ui";
 import type { MediaItem, Paginated } from "@/lib/types";
 
@@ -41,7 +42,6 @@ const ratingFilters = [
 export default function LibraryPage() {
   const [searchInput, setSearchInput] = useState("");
   const [search, setSearch] = useState("");
-  const [ordering, setOrdering] = useState("-created_at");
   const [page, setPage] = useState(1);
 
   const sidebarOpen = useUi((state) => state.sidebarOpen);
@@ -50,6 +50,21 @@ export default function LibraryPage() {
   const setRatings = useUi((state) => state.setRatings);
   const perPage = useUi((state) => state.perPage);
   const setPerPage = useUi((state) => state.setPerPage);
+  const ordering = useUi((state) => state.ordering);
+  const setOrdering = useUi((state) => state.setOrdering);
+
+  useEffect(() => {
+    function handleKeyDown(event: KeyboardEvent) {
+      if (event.key !== "/" || event.ctrlKey || event.metaKey || event.altKey) {
+        return;
+      }
+      if (isTypingTarget(event.target)) return;
+      event.preventDefault();
+      document.getElementById("library-search")?.focus();
+    }
+    window.addEventListener("keydown", handleKeyDown);
+    return () => window.removeEventListener("keydown", handleKeyDown);
+  }, []);
 
   const query = useQuery({
     queryKey: ["files", { search, ratings, ordering, perPage, page }],
@@ -100,6 +115,7 @@ export default function LibraryPage() {
         <div className="relative">
           <Search className="pointer-events-none absolute left-2.5 top-1/2 h-4 w-4 -translate-y-1/2 text-ctp-overlay0" />
           <input
+            id="library-search"
             className={cn(inputClass, "pl-8")}
             placeholder="Filename…"
             value={searchInput}