feat: initial scaffold for ClickTrack monorepo

Full self-hosted click track generator for cover bands.

Core technical pieces implemented:
- CTP (Click Track Protocol) TypeScript schema, Zod validator, and WAV
  renderer (44.1 kHz, 16-bit PCM, accented downbeats, ramp sections)
- MusicBrainz API client with 1 req/s rate limiting
- PostgreSQL schema (songs, tempo_maps, registry_sync_log) with triggers
- Git registry sync logic (clone/pull → validate CTP → upsert DB)
- Next.js 14 App Router: search page, track page, API routes
  (/api/songs, /api/tracks, /api/generate)
- UI components: SearchBar, SongResult, TempoMapEditor, ClickTrackPlayer
  (Web Audio API in-browser playback + WAV download)
- Docker Compose stack: app + postgres + redis + nginx + registry-sync
- Multi-stage Dockerfile with standalone Next.js output
- .env.example documenting all configuration variables
- README with setup instructions, CTP format spec, and API reference

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

app/(web)/page.tsx

@@ -0,0 +1,101 @@
+import { Suspense } from "react";
+import SearchBar from "@/components/SearchBar";
+import SongResult from "@/components/SongResult";
+import { searchSongs as searchSongsDB } from "@/lib/db/client";
+import { searchSongs as searchMB } from "@/lib/musicbrainz/client";
+import { upsertSong } from "@/lib/db/client";
+
+interface PageProps {
+  searchParams: { q?: string };
+}
+
+async function SearchResults({ q }: { q: string }) {
+  // Try local DB first
+  let songs = await searchSongsDB(q, 20);
+
+  // If sparse results, hit MusicBrainz and cache locally
+  if (songs.length < 3) {
+    try {
+      const mbResults = await searchMB(q, 20);
+      for (const s of mbResults) {
+        await upsertSong({
+          mbid: s.mbid,
+          title: s.title,
+          artist: s.artist,
+          duration_seconds: s.duration_seconds,
+          acousticbrainz_bpm: null,
+          acousticbrainz_time_sig_num: null,
+          source: "musicbrainz",
+        });
+      }
+      songs = await searchSongsDB(q, 20);
+    } catch {
+      // MusicBrainz unavailable — fall through with local results
+    }
+  }
+
+  if (songs.length === 0) {
+    return (
+      <p className="mt-8 text-center text-zinc-500">
+        No results for <span className="text-zinc-300">&ldquo;{q}&rdquo;</span>.
+        Try a different search.
+      </p>
+    );
+  }
+
+  return (
+    <ul className="mt-6 space-y-3">
+      {songs.map((song) => (
+        <SongResult key={song.mbid} song={song} />
+      ))}
+    </ul>
+  );
+}
+
+export default function HomePage({ searchParams }: PageProps) {
+  const q = searchParams.q?.trim() ?? "";
+
+  return (
+    <div>
+      <div className="mb-10 text-center">
+        <h1 className="text-4xl font-bold tracking-tight text-green-400">ClickTrack</h1>
+        <p className="mt-3 text-zinc-400">
+          Find a song, download a click track. Built for cover bands.
+        </p>
+      </div>
+
+      <SearchBar initialValue={q} />
+
+      {q && (
+        <Suspense
+          fallback={
+            <p className="mt-8 text-center text-zinc-500 animate-pulse">Searching…</p>
+          }
+        >
+          {/* @ts-expect-error async server component */}
+          <SearchResults q={q} />
+        </Suspense>
+      )}
+
+      {!q && (
+        <div className="mt-12 grid gap-6 text-sm text-zinc-500 sm:grid-cols-3">
+          <div className="rounded-lg border border-zinc-800 p-5">
+            <div className="mb-2 text-lg font-semibold text-zinc-200">Search</div>
+            Search any song by title or artist. We pull metadata from MusicBrainz
+            and cache it locally.
+          </div>
+          <div className="rounded-lg border border-zinc-800 p-5">
+            <div className="mb-2 text-lg font-semibold text-zinc-200">Tempo Map</div>
+            Community-contributed CTP tempo maps define every section, time
+            signature change, and tempo ramp in a song.
+          </div>
+          <div className="rounded-lg border border-zinc-800 p-5">
+            <div className="mb-2 text-lg font-semibold text-zinc-200">Download</div>
+            Generate a 44.1 kHz WAV click track with accented downbeats — ready
+            for your in-ear monitor mix.
+          </div>
+        </div>
+      )}
+    </div>
+  );
+}