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>

docker-compose.simple.yml

@@ -1,4 +1,4 @@
-# MMTL 单镜像部署模板（SQLite）
+# MeBox 单镜像部署模板（SQLite）
 #
 # 适合：新手、单人使用、低配 NAS / 小主机。
 # 特点：只有一个镜像，不需要 PostgreSQL / Redis / .env。
@@ -12,10 +12,10 @@
 # 首次登录后请立刻修改密码。
 
 services:
-  mmtl:
-    image: ghcr.io/truewhile/mmtl:latest
+  mebox:
+    image: ghcr.io/truewhile/mebox:latest
 
-    container_name: mmtl
+    container_name: mebox
     restart: unless-stopped
     init: true
 
@@ -62,29 +62,29 @@ services:
       PUID: "1000"
       PGID: "1000"
 
-      MMTL_APP_HOST: 0.0.0.0
-      MMTL_APP_PORT: 8080
-      MMTL_APP_WEB_DIR: /app/web/dist
-      MMTL_APP_DATA_DIR: /data
+      MEBOX_APP_HOST: 0.0.0.0
+      MEBOX_APP_PORT: 8080
+      MEBOX_APP_WEB_DIR: /app/web/dist
+      MEBOX_APP_DATA_DIR: /data
 
-      # 单镜像档固定使用 SQLite。主数据库文件：./data/mmtl.db。
-      MMTL_DATABASE_TYPE: sqlite
-      MMTL_DATABASE_DB_PATH: /data/mmtl.db
-      MMTL_CACHE_CACHE_DIR: /cache
+      # 单镜像档固定使用 SQLite。主数据库文件：./data/mebox.db。
+      MEBOX_DATABASE_TYPE: sqlite
+      MEBOX_DATABASE_DB_PATH: /data/mebox.db
+      MEBOX_CACHE_CACHE_DIR: /cache
 
       # 路径映射保持容器内统一，网页和下载器里优先使用 /media、/downloads。
-      MMTL_MEDIA_DIR: /media
-      MMTL_MEDIA_CONTAINER_DIR: /media
-      MMTL_DOWNLOAD_DIR: /downloads
-      MMTL_DOWNLOAD_CONTAINER_DIR: /downloads
+      MEBOX_MEDIA_DIR: /media
+      MEBOX_MEDIA_CONTAINER_DIR: /media
+      MEBOX_DOWNLOAD_DIR: /downloads
+      MEBOX_DOWNLOAD_CONTAINER_DIR: /downloads
 
       # 完整应用日志默认写入 ./data/logs/app.log；排查复杂问题时可临时改成 debug。
-      MMTL_LOGGING_LEVEL: info
-      MMTL_LOGGING_FORMAT: console
-      MMTL_LOGGING_OUTPUT_PATH: /data/logs
-      MMTL_LOGGING_MAX_SIZE_MB: "50"
-      MMTL_LOGGING_MAX_BACKUPS: "20"
-      MMTL_LOGGING_MAX_AGE_DAYS: "30"
+      MEBOX_LOGGING_LEVEL: info
+      MEBOX_LOGGING_FORMAT: console
+      MEBOX_LOGGING_OUTPUT_PATH: /data/logs
+      MEBOX_LOGGING_MAX_SIZE_MB: "50"
+      MEBOX_LOGGING_MAX_BACKUPS: "20"
+      MEBOX_LOGGING_MAX_AGE_DAYS: "30"
 
     extra_hosts:
       # 容器访问宿主机服务用，例如 qBittorrent: http://host.docker.internal:8085