feat(hh): ratatui TUI client — chat, live roster, themes

- Connect subcommand: SRP auth then a ratatui UI over tokio + crossterm.
- Async ws (tokio-tungstenite); reader task decrypts/parses frames into events.
- Panes: top bar (e2e + house N/cap), chat scrollback, roster (self marked ⛧),
  input box. Undecryptable frames surface as a system line, not a silent drop.
- Themes (vestments) via TOML --theme; default occult-monochrome + neon.
- Verified live in tmux: render, chat round-trip, roster, join/leave.
- Adds fernet python->rust interop regression test.

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

hh/Cargo.toml

@@ -26,6 +26,14 @@ tungstenite = { version = "0.24", features = ["rustls-tls-webpki-roots"] }
 rustls = "0.23"
 url = "2"
 
+# async + tui
+tokio = { version = "1", features = ["rt-multi-thread", "macros", "net", "io-util", "sync", "time"] }
+tokio-tungstenite = { version = "0.24", features = ["rustls-tls-webpki-roots"] }
+futures-util = "0.3"
+ratatui = { version = "0.29", features = ["serde"] }
+crossterm = { version = "0.28", features = ["event-stream"] }
+toml = "0.8"
+
 # data
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"