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/repo/contract/postgres_test.go

@@ -10,16 +10,16 @@ import (
 
 	"github.com/jackc/pgx/v5/pgxpool"
 
-	assets "shared-album"
-	"shared-album/internal/albums"
-	"shared-album/internal/auth"
-	"shared-album/internal/db"
-	"shared-album/internal/members"
-	"shared-album/internal/notifications"
-	"shared-album/internal/photos"
-	"shared-album/internal/settings"
-	"shared-album/internal/sharelinks"
-	"shared-album/internal/social"
+	assets "galo"
+	"galo/internal/albums"
+	"galo/internal/auth"
+	"galo/internal/db"
+	"galo/internal/members"
+	"galo/internal/notifications"
+	"galo/internal/photos"
+	"galo/internal/settings"
+	"galo/internal/sharelinks"
+	"galo/internal/social"
 )
 
 // TestPostgresContract runs the shared suite against PostgreSQL inside its own