chore: rename project coven → hack-house ⛧

Rebrand the Rust client crate (coven/ → hh/, package+binary "hack-house"),
README, CLI strings, and branch (coven → hack-house). Gitea repo renamed
cmd-chat → hack-house to match. Crypto/server logic unchanged; selftest +
golden-vector test still green, binary is now `hack-house`.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

hh/Cargo.toml

@@ -0,0 +1,35 @@
+[package]
+name = "hack-house"
+version = "0.1.0"
+edition = "2021"
+description = "hack-house — encrypted collaborative sessions with a summoned sandbox. ⛧"
+license = "MIT"
+
+[[bin]]
+name = "hack-house"
+path = "src/main.rs"
+
+[dependencies]
+# crypto
+num-bigint = "0.4"
+num-traits = "0.2"
+sha2 = "0.10"
+hkdf = "0.12"
+fernet = "0.2"
+base64 = "0.22"
+rand = "0.8"
+hex = "0.4"
+
+# net
+reqwest = { version = "0.12", default-features = false, features = ["blocking", "json", "rustls-tls"] }
+tungstenite = { version = "0.24", features = ["rustls-tls-webpki-roots"] }
+rustls = "0.23"
+url = "2"
+
+# data
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+
+# cli / errors
+clap = { version = "4", features = ["derive"] }
+anyhow = "1"