fix(shell): disable init logging by default

scripts/shell-init.sh

@@ -1,7 +1,22 @@
 # ---- logging ---------------------------------------------------------------
 
 log_shell_init() {
-  printf '%s\n' "shell-init: $*" >>/tmp/shell-init.log 2>/dev/null || true
+  # Disabled by default to avoid noisy permission errors in login shells.
+  # Enable with:
+  #   export NANUQSAURUS_SHELL_INIT_LOG=1
+  # Optionally override the file path:
+  #   export NANUQSAURUS_SHELL_INIT_LOG_FILE="$HOME/.local/state/shell-init.log"
+  [[ -n "${NANUQSAURUS_SHELL_INIT_LOG:-}" ]] || return 0
+
+  local uid="${UID:-}"
+  [[ -n "$uid" ]] || uid="$(id -u 2>/dev/null || echo unknown)"
+
+  local log_file="${NANUQSAURUS_SHELL_INIT_LOG_FILE:-${XDG_STATE_HOME:-$HOME/.local/state}/nanuqsaurus/shell-init-${uid}.log}"
+  local log_dir="${log_file%/*}"
+
+  mkdir -p "$log_dir" 2>/dev/null || return 0
+  # Redirect stderr first so a failing stdout redirection stays silent.
+  printf '%s\n' "shell-init: $*" 2>/dev/null >>"$log_file" || true
 }
 
 # ---- helpers ---------------------------------------------------------------