Add Lyra acquisition-engine design spec, README, gitignore

Initial design for slice 1 (acquisition engine): three-container
architecture (Next.js UI, Python worker, slskd), the six-stage
pipeline, source-adapter contract, data model, error handling, and
testing strategy.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

README.md

@@ -0,0 +1,30 @@
+# Lyra
+
+Self-hosted, multi-source music acquisition and library tool — a replacement for
+Lidarr + NZBget. Lyra discovers, ranks, downloads, tags, and organizes music across
+sources of differing quality: **Qobuz** (lossless/hi-res), **Soulseek** (P2P),
+**YouTube** (universal lossy fallback), and **Spotify** (discovery/metadata only).
+
+## Status
+
+Early design. Built in three slices:
+
+1. **Acquisition engine** — *in progress*. Given an album/track, find the best
+   available source, download it, tag it against MusicBrainz, and file it into a
+   clean library.
+2. **Library manager** — Lidarr-style monitoring, wanted lists, auto-grab of new
+   releases.
+3. **Discovery** — Spotify/recommendation-driven finding of new music.
+
+## Architecture
+
+Three Docker containers on a home server:
+
+- **Next.js app** — UI + API (search, request, queue, progress, settings).
+- **Python worker** — all source integration (streamrip, yt-dlp, slskd client,
+  beets/mutagen), running the six-stage acquisition pipeline.
+- **slskd** — off-the-shelf headless Soulseek daemon.
+
+**Postgres** is the shared source of truth; a shared `/music` volume is the library.
+
+See [`docs/superpowers/specs/`](docs/superpowers/specs/) for the full design.