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/themes/crypt.toml

@@ -0,0 +1,12 @@
+# crypt — churchofmalware occult monochrome (default)
+name = "crypt"
+border = "darkgray"
+title = "white"
+accent = "white"
+dim = "darkgray"
+me = "white"
+other = "gray"
+system = "darkgray"
+input = "white"
+roster_me = "white"
+roster_width = 22

hh/themes/neon.toml

@@ -0,0 +1,12 @@
+# neon — cyberpunk accents on black
+name = "neon"
+border = "#3a3a5a"
+title = "#e0e0ff"
+accent = "#ff2fd0"
+dim = "#5a5a7a"
+me = "#39ff14"
+other = "#00e5ff"
+system = "#7a5cff"
+input = "#39ff14"
+roster_me = "#ff2fd0"
+roster_width = 24