fix: refresh stale cellular source IP and resolve cpxy symlink BASE

WWAN re-dial often keeps iface name (wwan0) but changes private IP.
Stale inet4_bind_address then makes SOCKS rep=0x01 while the panel still
looks healthy. generate/cpxy now re-read live source IP on each regenerate.

Also fix /usr/local/bin/cpxy symlink: dirname($0) became /usr/local and
broke rebind/generate (missing lib.sh).

scripts/upgrade.sh

@@ -201,7 +201,16 @@ info "配置已确认 bind_interface=$cell"
 install -m 0755 /dev/stdin "$INSTALL_DIR/bin/cpxy" <<'EOF'
 #!/usr/bin/env bash
 set -euo pipefail
-BASE="$(cd "$(dirname "$0")/.." && pwd)"
+# 经 /usr/local/bin/cpxy 符号链接调用时，$0 仍是链接路径；必须 resolve 真实路径
+_self="${BASH_SOURCE[0]:-$0}"
+if command -v readlink >/dev/null 2>&1; then
+  _resolved="$(readlink -f "$_self" 2>/dev/null || true)"
+  [[ -n "$_resolved" ]] && _self="$_resolved"
+fi
+BASE="$(cd "$(dirname "$_self")/.." && pwd)"
+if [[ ! -d "$BASE/scripts" && -d /opt/cellular-proxy/scripts ]]; then
+  BASE="/opt/cellular-proxy"
+fi
 export CONFIG_FILE="${CONFIG_FILE:-$BASE/etc/settings.conf}"
 cmd="${1:-help}"
 shift || true
@@ -217,6 +226,13 @@ case "$cmd" in
         src="$(detect_source_ip "$cell" || true)"
         persist_cellular_to_settings "$CONFIG_FILE" "$cell" "$src"
         CELLULAR_IFACE="$cell"
+        CELLULAR_SOURCE_IP="${src:-}"
+      fi
+    elif [[ -n "${CELLULAR_IFACE:-}" ]]; then
+      src="$(detect_source_ip "$CELLULAR_IFACE" || true)"
+      if [[ -n "$src" && "${CELLULAR_SOURCE_IP:-}" != "$src" ]]; then
+        persist_cellular_to_settings "$CONFIG_FILE" "$CELLULAR_IFACE" "$src"
+        CELLULAR_SOURCE_IP="$src"
       fi
     fi
     "$BASE/scripts/generate.sh" "$BASE/generated"
@@ -235,7 +251,7 @@ case "$cmd" in
     [[ -n "$cell" ]] || die "未能探测数据网卡"
     src="$(detect_source_ip "$cell" || true)"
     persist_cellular_to_settings "$CONFIG_FILE" "$cell" "$src"
-    info "已重新绑定 $cell"
+    info "已重新绑定 $cell src=${src:-}"
     exec "$0" generate
     ;;
   upgrade)