feat: GuiPresence (chat-service presence backend, gateway route, mod module); restore TODO history

backend/chat-service/Cargo.toml

@@ -0,0 +1,23 @@
+[package]
+name = "chat-service"
+version = "0.1.0"
+edition = "2024"
+
+[lib]
+name = "chat_service"
+path = "src/lib.rs"
+
+[dependencies]
+common = { path = "../common" }
+axum = { version = "0.8", features = ["macros"] }
+tokio = { version = "1", features = ["rt-multi-thread", "macros", "time"] }
+tracing = "0.1"
+tracing-subscriber = "0.3"
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+uuid = { version = "1", features = ["v4", "serde"] }
+anyhow = "1"
+dotenvy = "0.15"
+
+[dev-dependencies]
+axum-test = "21"