Rebuild the UI on Next.js, and give search real metadata

The old page was hand-written HTML/CSS/JS. That was fine for a search box and
a list, but the roadmap here is multi-user, an admin dashboard with usage
graphs, and an import-review queue — all of which get painful in vanilla DOM
code. Moves to Next.js 16 / React 19 / Tailwind 4 / Framer Motion.

Built as a STATIC EXPORT served by FastAPI. Running `next start` alongside
uvicorn would add a Node runtime, a second process to supervise, and a second
thing that can be down while the other is up. There is no use for SSR — every
view is behind auth and renders from live JSON — so the deployment stays one
container, one process, one healthcheck. Image is 60MB; Node only exists in
the build stage.

Search now carries what a music UI needs:

- year and genre, grafted on from /album/{id} concurrently, deduplicated by
  album and cached forever since a release date is immutable
- 30-second previews, so you can hear a track before committing a Soulseek
  search to it. Not a library player — that is Navidrome's job.
- autocomplete over songs/albums/artists, debounced and aborted per keystroke
  so a slow response to "rad" cannot land after "radiohead"
- album and artist pages, with `Get all` to queue a release in one request
- the accent colour is sampled from the artwork, so the palette follows the
  music. Deezer's CDN sends ACAO:*, which is what makes canvas sampling work
  with no image proxy.

/api/album/{id} deliberately calls Deezer twice: the track list embedded in
the album response has no track_position, and using the list index instead
misnumbers every multi-disc release — verified against the White Album, where
disc 2 track 1 would have been filed as 18.

Schema is multi-user ready ahead of the feature: users table with roles and
quotas, requested_by on jobs, and the first login becomes admin. Auth is still
the single-user GitHub allowlist.

CSP survives all of this intact. Next emits inline hydration scripts, which
script-src 'self' blocks; rather than per-request nonces, their SHA-256 is
computed at startup from the built page — a static export never varies between
requests, so hashes need no maintenance and no HTML rewriting. The one
concession is style-src-attr 'unsafe-inline', because Framer Motion writes its
pre-hydration state into style="" and without it every element flashes in.
That permits style attributes only. img-src/media-src now name Deezer's CDN
explicitly instead of allowing https: wholesale, closing an exfiltration
channel that survived connect-src 'self'. /_next/* sits behind the session
too — there is no local login page to style, so the bundle need not be public.

Verified: unauthenticated /→302 and every /api/*→401 including the four new
endpoints, forged state→400, forged cookie→401, misconfigured auth refuses to
start, and the production image hydrates with zero CSP violations.

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

web/components/hero.tsx

@@ -0,0 +1,88 @@
+"use client";
+
+import { motion } from "framer-motion";
+import { cn } from "@/lib/utils";
+
+/**
+ * Album/artist header. The artwork itself, blown up and blurred, is the
+ * panel's own backdrop — cheaper and more faithful than trying to synthesise
+ * a gradient from the extracted accent, and it reads as the record rather
+ * than as a themed box.
+ */
+export function Hero({
+  kind,
+  title,
+  art,
+  round,
+  by,
+  facts,
+  actions,
+}: {
+  kind: string;
+  title: string;
+  art: string | null;
+  round?: boolean;
+  by?: React.ReactNode;
+  facts?: (string | null | undefined)[];
+  actions?: React.ReactNode;
+}) {
+  return (
+    <motion.div
+      initial={{ opacity: 0, y: 14 }}
+      animate={{ opacity: 1, y: 0 }}
+      transition={{ type: "spring", stiffness: 300, damping: 30 }}
+      className="glass relative mb-5 flex flex-col sm:flex-row items-center sm:items-stretch
+                 gap-4 sm:gap-5 overflow-hidden rounded-panel p-5 text-center sm:text-left"
+    >
+      {art && (
+        /* eslint-disable-next-line @next/next/no-img-element */
+        <img
+          src={art}
+          alt=""
+          aria-hidden
+          className="absolute inset-0 z-0 h-full w-full scale-[1.35] object-cover
+                     opacity-40 blur-[46px] saturate-[1.8]"
+        />
+      )}
+      <div className="absolute inset-0 z-[1] bg-gradient-to-r from-[var(--scrim)] to-[var(--scrim-2)]" />
+
+      {art && (
+        <motion.img
+          layoutId={`art-${title}`}
+          src={art}
+          alt=""
+          className={cn(
+            "relative z-[2] w-[132px] h-[132px] sm:w-[150px] sm:h-[150px] shrink-0 object-cover",
+            "bg-faint shadow-[0_14px_40px_rgb(0_0_0/0.5)]",
+            round ? "rounded-full" : "rounded-2xl",
+          )}
+        />
+      )}
+
+      <div className="relative z-[2] flex min-w-0 flex-1 flex-col justify-center">
+        <div className="mb-1.5 text-[11px] font-bold uppercase tracking-[1px] text-accent">
+          {kind}
+        </div>
+        <h2 className="mb-2 text-2xl sm:text-[29px] font-bold leading-[1.14] tracking-[-0.8px]">
+          {title}
+        </h2>
+        {by && <div className="mb-2.5 text-[15px] font-semibold">{by}</div>}
+        {facts && (
+          <div className="mb-3.5 flex flex-wrap justify-center sm:justify-start gap-1.5">
+            {facts.filter(Boolean).map((f, i) => (
+              <span
+                key={i}
+                className="glass-hi rounded-full px-2.5 py-0.5 text-[11.5px] text-dim"
+              >
+                {f}
+              </span>
+            ))}
+          </div>
+        )}
+        {actions && (
+          <div className="flex flex-wrap justify-center sm:justify-start gap-2.5">{actions}</div>
+        )}
+      </div>
+    </motion.div>
+  );
+}