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.

frontend/src/generated/examples.ts

@@ -234,6 +234,7 @@ export const EXAMPLES: Record<string, unknown> = {
     "publicKey": "",
     "reset": 0,
     "reverse": null,
+    "secret": "ee1234567890abcdef1234567890abcd7777772e636c6f7564666c6172652e636f6d",
     "security": "",
     "subId": "",
     "tgId": 0,
@@ -265,6 +266,7 @@ export const EXAMPLES: Record<string, unknown> = {
     "publicKey": "",
     "reset": 0,
     "reverse": null,
+    "secret": "",
     "security": "",
     "subId": "",
     "tgId": 0,
@@ -402,6 +404,7 @@ export const EXAMPLES: Record<string, unknown> = {
     "enable": true,
     "id": 1,
     "listen": "",
+    "mtprotoDomain": "",
     "nodeAddress": "",
     "nodeId": null,
     "port": 443,