Rebrand MMTL to MeBox (name, logo, Docker image) (#17)

* Rebrand MMTL to MeBox across codebase and assets

Rename the project display name, Go module path, environment variable
prefix (MEBOX_*), Docker image references, and UI branding from MMTL/mmtl
to MeBox/mebox. Replace logo assets with the new MeBox icon and keep
legacy SQLite migration support for existing mmtl.db deployments.

Co-authored-by: truewhile <truewhile@users.noreply.github.com>

* Fix logo icons: use cube-only crop without truncated text

Previous icon generation cropped too much of the source image, including
partial MeBox wordmark text that was cut off in square icon containers.
Regenerate logo-64/192/512, favicon, and SVG from cube-only region.

Co-authored-by: truewhile <truewhile@users.noreply.github.com>

---------

Co-authored-by: Cursor Agent <cursoragent@cursor.com>
Co-authored-by: truewhile <truewhile@users.noreply.github.com>

internal/service/scanner_incremental_test.go

@@ -10,9 +10,9 @@ import (
 	"go.uber.org/zap"
 	"gorm.io/gorm"
 
-	"github.com/ShukeBta/MMTL/internal/config"
-	"github.com/ShukeBta/MMTL/internal/model"
-	"github.com/ShukeBta/MMTL/internal/repository"
+	"github.com/truewhile/MeBox/internal/config"
+	"github.com/truewhile/MeBox/internal/model"
+	"github.com/truewhile/MeBox/internal/repository"
 )
 
 func newScannerTestEnv(t *testing.T) (*ScannerService, *repository.Container) {
@@ -425,8 +425,8 @@ func TestScanLibraryMapsPersistedHostLibraryPath(t *testing.T) {
 	if err := os.WriteFile(file, []byte("episode"), 0o644); err != nil {
 		t.Fatal(err)
 	}
-	t.Setenv("MMTL_MEDIA_DIR", `Q:\media`)
-	t.Setenv("MMTL_MEDIA_CONTAINER_DIR", containerRoot)
+	t.Setenv("MEBOX_MEDIA_DIR", `Q:\media`)
+	t.Setenv("MEBOX_MEDIA_CONTAINER_DIR", containerRoot)
 
 	lib := model.Library{Name: "国产剧", Path: `Q:\media\电视剧\国产剧`, Type: "tv", Enabled: true}
 	if err := repos.Library.Create(t.Context(), &lib); err != nil {