fix: bundle extensions directory for memory-core plugin

The clawdbot gateway expects bundled plugins (like memory-core) to be
available in an extensions directory. This change:

1. Copies the extensions/ directory to $out/lib/clawdbot/ during install
2. Sets CLAWDBOT_BUNDLED_PLUGINS_DIR env var so clawdbot can discover them

Without this fix, users get "plugin not found: memory-core" errors when
using the default plugins.slots.memory configuration.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: nycterent

nix/scripts/gateway-install.sh

@@ -2,8 +2,14 @@
 set -e
 mkdir -p "$out/lib/clawdbot" "$out/bin"
 
+# Copy core files
 cp -r dist node_modules package.json ui "$out/lib/clawdbot/"
 
+# Copy bundled extensions (memory-core, etc.) if present
+if [ -d "extensions" ]; then
+  cp -r extensions "$out/lib/clawdbot/"
+fi
+
 if [ -z "${STDENV_SETUP:-}" ]; then
   echo "STDENV_SETUP is not set" >&2
   exit 1
@@ -34,4 +40,4 @@ if [ -n "$strip_ansi_src" ]; then
     ln -s "$strip_ansi_src" "$out/lib/clawdbot/node_modules/strip-ansi"
   fi
 fi
-bash -e -c '. "$STDENV_SETUP"; makeWrapper "$NODE_BIN" "$out/bin/clawdbot" --add-flags "$out/lib/clawdbot/dist/index.js" --set-default CLAWDBOT_NIX_MODE "1"'
+bash -e -c '. "$STDENV_SETUP"; makeWrapper "$NODE_BIN" "$out/bin/clawdbot" --add-flags "$out/lib/clawdbot/dist/index.js" --set-default CLAWDBOT_NIX_MODE "1" --set-default CLAWDBOT_BUNDLED_PLUGINS_DIR "$out/lib/clawdbot/extensions"'