feat: implement core Roku ECP adapter

Add SSDP discovery plus the main ECP app, state, and key control flows so
Milestone 2 has a working Roku foundation with parser and key-mapping tests.

Cargo.toml

@@ -8,6 +8,8 @@ anyhow = "1.0"
 axum = "0.8"
 chrono = { version = "0.4", features = ["serde"] }
 clap = { version = "4.5", features = ["derive"] }
+reqwest = { version = "0.12", default-features = false, features = ["charset", "http2", "json", "multipart", "rustls-tls"] }
+roxmltree = "0.20"
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 thiserror = "2.0"
@@ -15,4 +17,5 @@ tokio = { version = "1.0", features = ["full"] }
 toml = "0.8"
 tracing = "0.1"
 tracing-subscriber = { version = "0.3", features = ["env-filter", "fmt"] }
+urlencoding = "2.1"
 uuid = { version = "1.0", features = ["serde", "v4"] }