feat: rename service to galo, add halo branding and release build

- rename Go module, binary, systemd unit, PG_DATABASE default, frontend package and docs from shared-album to galo
- add theme-aware halo emblem and favicon (new ui-branding capability)
- add make build-release (versioned, stripped, static binary) and run the binary from the repo root

backend/internal/config/config.go

@@ -131,7 +131,7 @@ func Load() (*Config, error) {
 			Port:     pgPort,
 			User:     getEnv("PG_USER", "album"),
 			Password: getEnv("PG_PASSWORD", ""),
-			Database: getEnv("PG_DATABASE", "shared_album"),
+			Database: getEnv("PG_DATABASE", "galo"),
 			SSLMode:  getEnv("PG_SSLMODE", "disable"),
 		},
 		S3: S3{