feat(api): library sources, scanner and catalog (M2)

- schema for sources, path patterns, media files, artists, albums,
  tracks, genres (migration 00003)
- path patterns (RE2 with named groups, skip), merge with tags by
  source priority, fallbacks from the file name and folder, name
  normalization and multi-artist split
- scanner: walk, skip unchanged files by size and mtime, ffprobe in 8
  workers with a single catalog writer, renames by content hash keep
  the track, duplicates fold into one track with the best file as
  primary, missing files are kept 30 days
- storage-agent mounts NFS with validated server, export and an option
  whitelist, no shell; test mount counts audio files
- admin API: sources CRUD, connection test, patterns with preview,
  scan, library status, file errors, host folder picker; scheduled
  scans and health checks; mounts are restored on start
- catalog API: artist, artist albums, album with tracks, track
- api image is alpine with ffmpeg for ffprobe

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

services/api/cmd/api/main.go

@@ -9,12 +9,14 @@ import (
 	"os"
 	"os/signal"
 	"syscall"
+	"time"
 
 	"github.com/jackc/pgx/v5/pgxpool"
 	"github.com/redis/go-redis/v9"
 
 	"pipu/api/internal/auth"
 	"pipu/api/internal/buildinfo"
+	"pipu/api/internal/library"
 	"pipu/api/internal/platform/config"
 	"pipu/api/internal/platform/db"
 	"pipu/api/internal/platform/httpx"
@@ -78,11 +80,21 @@ func run() error {
 		"redis":    system.CheckerFunc(func(ctx context.Context) error { return rdb.Ping(ctx).Err() }),
 	})
 
+	libStore := library.NewStore(pool)
+	prober := library.FFprobe{Bin: cfg.FFprobePath, Timeout: time.Minute}
+	board := library.NewProgressBoard()
+	scanner := library.NewScanner(libStore, prober, board, log)
+	libSvc := library.NewService(libStore, scanner, board, library.NewHTTPAgent(cfg.StorageAgentURL, cfg.InternalToken),
+		prober, library.Config{LibraryRoot: cfg.LibraryRoot, HostRoot: cfg.LibraryHostRoot}, log)
+	go libSvc.Restore(ctx)
+	go libSvc.RunSchedule(ctx)
+
 	srv := httpx.NewServer(cfg.HTTPAddr, server.NewRouter(server.Deps{
 		Log:         log,
 		System:      sys,
 		Auth:        auth.NewHandler(authSvc, cfg.CookieSecure),
 		AuthService: authSvc,
+		Library:     library.NewHandler(libSvc, libStore),
 	}))
 	log.Info("starting", "version", buildinfo.Version)
 	return httpx.Serve(ctx, log, srv, cfg.ShutdownTimeout)