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/backfill-exif/main.go

@@ -7,11 +7,11 @@ import (
 	"os"
 	"strings"
 
-	"shared-album/internal/config"
-	"shared-album/internal/db"
-	"shared-album/internal/settings"
-	"shared-album/internal/storage"
-	"shared-album/internal/store"
+	"galo/internal/config"
+	"galo/internal/db"
+	"galo/internal/settings"
+	"galo/internal/storage"
+	"galo/internal/store"
 )
 
 func main() {