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/handler/system_meta.go

@@ -15,7 +15,7 @@ import (
 	"github.com/shirou/gopsutil/v3/disk"
 	"github.com/shirou/gopsutil/v3/mem"
 
-	"github.com/ShukeBta/MMTL/internal/service"
+	"github.com/truewhile/MeBox/internal/service"
 )
 
 // startedAt is captured at first call so /system/status can report uptime
@@ -31,7 +31,7 @@ func systemInfoHandler(svc *service.Container) gin.HandlerFunc {
 			}
 		}
 		c.JSON(http.StatusOK, gin.H{
-			"name":             "MMTL",
+			"name":             "MeBox",
 			"version":          "0.1.0",
 			"go":               runtime.Version(),
 			"os":               runtime.GOOS,