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/auth_tokens.go

@@ -9,7 +9,7 @@ import (
 
 	"github.com/golang-jwt/jwt/v5"
 
-	"github.com/ShukeBta/MMTL/internal/model"
+	"github.com/truewhile/MeBox/internal/model"
 )
 
 // IssueToken signs a JWT for the given user (60min validity, includes tier).
@@ -21,7 +21,7 @@ func (s *AuthService) IssueToken(u *model.User) (string, error) {
 		RegisteredClaims: jwt.RegisteredClaims{
 			IssuedAt:  jwt.NewNumericDate(time.Now()),
 			ExpiresAt: jwt.NewNumericDate(time.Now().Add(60 * time.Minute)),
-			Issuer:    "mmtl",
+			Issuer:    "mebox",
 			Subject:   u.ID,
 		},
 	}
@@ -68,7 +68,7 @@ func (s *AuthService) IssueExternalPlaybackToken(u *model.User, mediaID string,
 		RegisteredClaims: jwt.RegisteredClaims{
 			IssuedAt:  jwt.NewNumericDate(time.Now()),
 			ExpiresAt: jwt.NewNumericDate(time.Now().Add(ExternalPlaybackTokenDurationForMedia(durationSec))),
-			Issuer:    "mmtl",
+			Issuer:    "mebox",
 			Subject:   u.ID,
 		},
 	}
@@ -95,7 +95,7 @@ func (s *AuthService) IssueEmbyToken(u *model.User) (string, error) {
 		RegisteredClaims: jwt.RegisteredClaims{
 			IssuedAt:  jwt.NewNumericDate(time.Now()),
 			ExpiresAt: jwt.NewNumericDate(time.Now().Add(EmbyTokenDuration)),
-			Issuer:    "mmtl",
+			Issuer:    "mebox",
 			Subject:   u.ID,
 		},
 	}