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>

.venv/bin/pytest

@@ -0,0 +1,6 @@
+#!/home/dell/coding/learning/cmd-chat/.venv/bin/python3
+import sys
+from pytest import console_main
+if __name__ == '__main__':
+    sys.argv[0] = sys.argv[0].removesuffix('.exe')
+    sys.exit(console_main())