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>

components/SearchBar.tsx

@@ -0,0 +1,42 @@
+"use client";
+
+import { useRouter, useSearchParams } from "next/navigation";
+import { useTransition, useState } from "react";
+
+interface SearchBarProps {
+  initialValue?: string;
+}
+
+export default function SearchBar({ initialValue = "" }: SearchBarProps) {
+  const router = useRouter();
+  const [value, setValue] = useState(initialValue);
+  const [isPending, startTransition] = useTransition();
+
+  function handleSubmit(e: React.FormEvent) {
+    e.preventDefault();
+    if (!value.trim()) return;
+    startTransition(() => {
+      router.push(`/?q=${encodeURIComponent(value.trim())}`);
+    });
+  }
+
+  return (
+    <form onSubmit={handleSubmit} className="flex gap-3">
+      <input
+        type="search"
+        value={value}
+        onChange={(e) => setValue(e.target.value)}
+        placeholder="Search by song title or artist…"
+        className="flex-1 rounded-lg border border-zinc-700 bg-zinc-900 px-4 py-3 text-zinc-100 placeholder:text-zinc-600 focus:border-green-500 focus:outline-none focus:ring-1 focus:ring-green-500"
+        autoFocus
+      />
+      <button
+        type="submit"
+        disabled={isPending || !value.trim()}
+        className="rounded-lg bg-green-600 px-6 py-3 font-semibold text-white hover:bg-green-500 disabled:opacity-50 disabled:cursor-not-allowed transition-colors"
+      >
+        {isPending ? "Searching…" : "Search"}
+      </button>
+    </form>
+  );
+}