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_scan.go

@@ -9,7 +9,7 @@ import (
 
 	"go.uber.org/zap"
 
-	"github.com/ShukeBta/MMTL/internal/model"
+	"github.com/truewhile/MeBox/internal/model"
 )
 
 // ScanLibrary walks the library root and persists discovered media files.
@@ -100,8 +100,8 @@ func (s *ScannerService) scanLibrary(ctx context.Context, libraryID string, auto
 				zap.String("root_id", root.ID),
 				zap.String("path", root.Path),
 				zap.Strings("candidates", mappedPathCandidates(root.Path)),
-				zap.String("media_dir_env", os.Getenv("MMTL_MEDIA_DIR")),
-				zap.String("media_container_env", envOrDefault("MMTL_MEDIA_CONTAINER_DIR", "/media")),
+				zap.String("media_dir_env", os.Getenv("MEBOX_MEDIA_DIR")),
+				zap.String("media_container_env", envOrDefault("MEBOX_MEDIA_CONTAINER_DIR", "/media")),
 				zap.String("diagnostic", diag),
 				zap.Error(err))
 			if scanErr == nil {