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/repo_test.go

@@ -8,12 +8,12 @@ import (
 
 	"github.com/jackc/pgx/v5/pgxpool"
 
-	"shared-album/internal/albums"
-	"shared-album/internal/auth"
-	"shared-album/internal/members"
-	"shared-album/internal/models"
-	"shared-album/internal/photos"
-	"shared-album/internal/sharelinks"
+	"galo/internal/albums"
+	"galo/internal/auth"
+	"galo/internal/members"
+	"galo/internal/models"
+	"galo/internal/photos"
+	"galo/internal/sharelinks"
 )
 
 func testPool(t *testing.T) *pgxpool.Pool {