Initial commit: split VNOX monorepo into VNOX-Server

Unified server binary (vnox-serverd) combining:
- Gateway (TCP, auth, channels, sessions, SQLite)
- Voice-node (UDP relay, Opus, jitter buffer)

Standalone gateway (vnox-gateway) and voice-node (vnox-voice-node) preserved as sub-crates.

gateway/Cargo.toml

@@ -0,0 +1,40 @@
+[package]
+name        = "vnox-gateway"
+description = "VNOX gateway — auth, channels, sessions, permissions"
+version.workspace    = true
+edition.workspace    = true
+license.workspace    = true
+authors.workspace    = true
+repository.workspace = true
+
+[lib]
+name = "vnox_gateway"
+path = "src/lib.rs"
+
+[[bin]]
+name = "vnox-gateway"
+path = "src/main.rs"
+
+[dependencies]
+tokio.workspace              = true
+serde.workspace              = true
+serde_json.workspace         = true
+ed25519-dalek.workspace      = true
+x25519-dalek.workspace       = true
+chacha20poly1305.workspace   = true
+hkdf.workspace               = true
+sha2.workspace               = true
+argon2.workspace             = true
+rand.workspace               = true
+tracing.workspace            = true
+tracing-subscriber.workspace = true
+anyhow.workspace             = true
+thiserror.workspace          = true
+toml.workspace               = true
+uuid.workspace               = true
+hex.workspace                = true
+
+axum  = { version = "0.8", features = ["ws"] }
+tower = "0.5"
+sqlx     = { version = "0.9", features = ["sqlite", "runtime-tokio", "tls-rustls"] }
+bitflags = "2"