feat(mtproto): adopt dolonet/mtg-multi and make MTProto inbounds multi-client

Replace the upstream 9seconds/mtg sidecar with the dolonet/mtg-multi fork so a single MTProto inbound can serve many per-user secrets. Each panel client is now one named FakeTLS secret in the fork's [secrets] section: clients are first-class (attach/detach, limits, expiry, per-client tg:// links) exactly like every other protocol, mirroring the WireGuard multi-client model. Per-client traffic and online status come from the fork's /stats JSON API (its Prometheus output has no per-user label), fed into the existing email-keyed client_traffics accumulator; an optional throttle caps concurrent connections. A one-time seeder converts each legacy single-secret inbound into a one-client inbound.

The fork ships only linux/darwin amd64/arm64 binaries but is pure Go, so provisioning builds it from source for every supported platform (release.yml, DockerInit.sh) while keeping the panel-expected mtg-<os>-<arch> filename and the 'run' verb, so process.go is untouched. Also fixes a pre-existing update.sh gap that never renamed the mtg binary for armv6/armv7 updates.

internal/web/translation/zh-TW.json

@@ -522,6 +522,9 @@
         "mtgRouteOutbound": "出站",
         "mtgRouteOutboundHint": "選填。強制 Telegram 流量經由此出站（或負載平衡器）送出。留空則由您的路由規則決定。",
         "mtgRouteOutboundPlaceholder": "使用路由規則",
+        "mtprotoFakeTlsDomainHint": "產生新用戶端金鑰時使用的預設 FakeTLS 網域。每個用戶端可使用各自的網域。",
+        "mtgThrottleMaxConnections": "最大連線數",
+        "mtgThrottleMaxConnectionsHint": "以公平分配限制所有使用者的並行連線數。0 表示不限制。",
         "visionTestseed": "Vision testseed",
         "version": "版本",
         "udpIdleTimeout": "UDP 閒置逾時 (s)",
@@ -907,6 +910,8 @@
       "wireguardPreSharedKey": "WireGuard 預共用金鑰",
       "wireguardAllowedIPs": "WireGuard 允許的 IP",
       "wireguardAllowedIPsHint": "留空則自動分配；多個條目用逗號分隔",
+      "mtprotoSecret": "MTProto 金鑰",
+      "mtprotoSecretHint": "該用戶端的 FakeTLS 金鑰。重新產生即可更換。",
       "reverseTag": "反向標籤",
       "reverseTagPlaceholder": "選用 Reverse tag",
       "telegramId": "Telegram 使用者 ID",