refactor!: rebrand bterminal to agor (agents-orchestrator)

Rename Cargo crates (bterminal-core→agor-core, bterminal-relay→agor-relay),
env vars (BTERMINAL_*→AGOR_*), config paths (~/.config/agor), CSS custom
properties, plugin API object, package names, and all documentation.

BREAKING CHANGE: config/data paths changed from bterminal to agor.

agor-relay/Cargo.toml

@@ -0,0 +1,24 @@
+[package]
+name = "agor-relay"
+version = "0.1.0"
+edition = "2021"
+description = "Remote relay server for Agents Orchestrator multi-machine support"
+license = "MIT"
+
+[[bin]]
+name = "agor-relay"
+path = "src/main.rs"
+
+[dependencies]
+agor-core = { path = "../agor-core" }
+serde = { version = "1.0", features = ["derive"] }
+serde_json = "1.0"
+log = "0.4"
+env_logger = "0.11"
+tokio = { version = "1", features = ["full"] }
+tokio-tungstenite = { version = "0.21", features = ["native-tls"] }
+tokio-native-tls = "0.3"
+native-tls = "0.2"
+futures-util = "0.3"
+clap = { version = "4", features = ["derive"] }
+uuid = { version = "1", features = ["v4"] }