feat: add staged release updates

scripts/tallynote-update-runner.sh

@@ -22,6 +22,26 @@ die() { printf 'tallynote update runner: %s\n' "$*" >&2; exit 1; }
 old_target=$(readlink -f -- "$CURRENT_LINK")
 [[ "$old_target" == "$PREFIX/releases/"* && -d "$old_target" ]] || die 'current release target is invalid'
 
+request_operation='apply'
+if [[ -f "$REQUEST_FILE" && ! -L "$REQUEST_FILE" ]]; then
+  request_operation=$(sed -n 's/.*"operation"[[:space:]]*:[[:space:]]*"\(download\|apply\)".*/\1/p' "$REQUEST_FILE" | head -n 1)
+  [[ "$request_operation" == download || "$request_operation" == apply ]] || request_operation='apply'
+fi
+
+# Downloading is intentionally handled while the main service remains up.
+# The CLI persists the validated payload under the root-owned workspace and
+# leaves the job staged for a later apply request.
+if [[ "$request_operation" == download ]]; then
+  node_bin="$CURRENT_LINK/runtime/bin/node"
+  [[ -x "$node_bin" ]] || node_bin=$(command -v node || true)
+  [[ -n "$node_bin" ]] || die 'node runtime not found'
+  cli="$CURRENT_LINK/dist/server/cli/update.js"
+  [[ -f "$cli" ]] || die 'update CLI not found in current release'
+  "$node_bin" "$cli" --request-file "$REQUEST_FILE" || exit $?
+  rm -f -- "$REQUEST_FILE"
+  exit 0
+fi
+
 was_active=0
 if systemctl is-active --quiet "$SERVICE_NAME"; then was_active=1; fi
 # shellcheck disable=SC2329 # invoked indirectly by the EXIT trap below