feat(server/m7-353): config + main.go wiring for coverart enricher

internal/config/config.go

@@ -69,8 +69,11 @@ type AdminBootstrapConfig struct {
 }
 
 type LibraryConfig struct {
-	ScanPaths     []string `yaml:"scan_paths"`
-	ScanOnStartup bool     `yaml:"scan_on_startup"`
+	ScanPaths           []string `yaml:"scan_paths"`
+	ScanOnStartup       bool     `yaml:"scan_on_startup"`
+	CoverArtFromMBCAA   bool     `yaml:"coverart_from_mbcaa"`   // default true
+	CoverArtBackfillCap int      `yaml:"coverart_backfill_cap"` // default 500
+	ContactEmail        string   `yaml:"contact_email"`         // optional override for MBCAA UA
 }
 
 // SubsonicConfig controls wire-format concessions on the /rest/* surface.
@@ -134,6 +137,10 @@ func Default() Config {
 			RadioSize:           50,
 			RadioSizeMax:        200,
 		},
+		Library: LibraryConfig{
+			CoverArtFromMBCAA:   true,
+			CoverArtBackfillCap: 500,
+		},
 	}
 }
 
@@ -189,6 +196,19 @@ func applyEnv(cfg *Config) {
 			cfg.Library.ScanOnStartup = b
 		}
 	}
+	if v, ok := os.LookupEnv("MINSTREL_LIBRARY_COVERART_FROM_MBCAA"); ok {
+		if b, err := strconv.ParseBool(v); err == nil {
+			cfg.Library.CoverArtFromMBCAA = b
+		}
+	}
+	if v, ok := os.LookupEnv("MINSTREL_LIBRARY_COVERART_BACKFILL_CAP"); ok {
+		if n, err := strconv.Atoi(v); err == nil {
+			cfg.Library.CoverArtBackfillCap = n
+		}
+	}
+	if v, ok := os.LookupEnv("MINSTREL_CONTACT_EMAIL"); ok {
+		cfg.Library.ContactEmail = v
+	}
 	if v, ok := os.LookupEnv("MINSTREL_SUBSONIC_ALLOW_PLAINTEXT_PASSWORD"); ok {
 		if b, err := strconv.ParseBool(v); err == nil {
 			cfg.Subsonic.AllowPlaintextPassword = b