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/social/repository.go

@@ -3,7 +3,7 @@ package social
 import (
 	"context"
 
-	"shared-album/internal/models"
+	"galo/internal/models"
 )
 
 // Repository is the persistence contract for the social domain.