test(mtproto): cover single-backend DC aliases

Follow up gramsrv PR #17 with boundary coverage and public configuration docs.

Canonical-Telesrv: b4df3e72c24470e4ce09e5fc1d46e0c2944f6d3e

Reviewed-Head: e7eb07b9eb

Co-authored-by: onysd <beatvin128@gmail.com>

internal/config/config.go

@@ -31,12 +31,10 @@ type Config struct {
 	RSAKeyPath string
 	// DC 是本 server 的 DC ID。
 	DC int
-	// StrictDCCheck turns on exact DC-ID validation for the permanent-key
-	// exchange (default off = lenient). See mtprotoedge.Options.StrictDC doc
-	// for the full rationale: telesrv is always a single physical backend, but
-	// many client forks alias dc_id 1..5 to it, so a mismatched client-chosen
-	// dc_id is expected, not an attack — strict mode exists only for a
-	// hypothetical future real multi-DC deployment.
+	// StrictDCCheck enables the default-off key-exchange DC-label diagnostic.
+	// The normal single-backend mode accepts every wire int32 label without
+	// partitioning auth keys, sessions, or business state. See
+	// mtprotoedge.Options.StrictDC for the optional strict behavior.
 	StrictDCCheck bool
 	// MTProtoMaxConnections / PerIP 覆盖 raw Accept、codec sniff、握手到认证 session
 	// 的完整物理连接生命周期；负数关闭对应 admission 上限。