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/cmd/migrate/main.go

@@ -5,9 +5,9 @@ import (
 	"log/slog"
 	"os"
 
-	assets "shared-album"
-	"shared-album/internal/config"
-	"shared-album/internal/db"
+	assets "galo"
+	"galo/internal/config"
+	"galo/internal/db"
 )
 
 func main() {