Fix: seed pip into uv-created venv so MCP connector dep install works

uv venv does not bundle pip by default (unlike python3 -m venv), so when the
venv python was on PATH, ensure_installed_host's 'python3 -m pip install' failed
with 'No module named pip'. Apply --seed across the 4 copies of the venv-setup
block (install.sh, install-nightly.sh, run.sh, run-docker.sh).

install-nightly.sh

@@ -258,7 +258,7 @@ REQUIREMENTS="${INSTALL_DIR}/requirements.txt"
 
 if [ ! -f "$VENV_DIR/bin/python3" ]; then
     if command -v uv >/dev/null 2>&1; then
-        uv venv "$VENV_DIR" && uv pip install -r "$REQUIREMENTS" \
+        uv venv --seed "$VENV_DIR" && uv pip install -r "$REQUIREMENTS" \
             && info "✔ Python venv ready (uv)" \
             || warn "Python venv setup failed — Python MCP servers will be unavailable."
     elif command -v python3 >/dev/null 2>&1; then