fix(e2e): mark openclaw peer as optional to fix install on 2026.5.18

openclaw@2026.5.18 removed --omit=peer from the npm install it runs in
the plugin staging directory (see install-package-dir-CBciXqgD.js).
That makes npm 7+ auto-install peerDependencies, planting a real
node_modules/openclaw/ directory in the staging area. A new safety
check in plugin-peer-link refuses to overwrite a non-symlink directory
at the peer-link path, so the symlink never gets created and the
install fails with:

  Installed plugin opik-openclaw declares openclaw as a peer dependency,
  but OpenClaw could not create a plugin-local node_modules/openclaw link.

The install env explicitly sets npm_config_legacy_peer_deps=false, so
shipping a .npmrc with legacy-peer-deps=true in the tarball would not
help (env vars override .npmrc). And --ignore-scripts is hardcoded, so
postinstall cleanup hooks cannot run.

Fix: declare openclaw as an optional peer via peerDependenciesMeta.
npm 7+ honors this by NOT auto-installing optional peers, so the
phantom node_modules/openclaw never appears and the symlink step
succeeds cleanly. The peerDependencies declaration is kept so the
openclaw plugin install pipeline still recognizes openclaw as a peer
and creates the symlink at runtime (it filters on Object.keys of
peerDependencies, not on optional metadata).

Verified locally with the exact env vars openclaw 2026.5.18 sets
(legacy_peer_deps=false, strict_peer_deps=false): npm install only
creates the 119 legitimate runtime packages, no openclaw directory.

This also unblocks fresh user installs on openclaw 2026.5.18+, not
just CI.

Author: YarivHashaiComet

package.json

@@ -32,6 +32,11 @@
   "peerDependencies": {
     "openclaw": ">=2026.3.2"
   },
+  "peerDependenciesMeta": {
+    "openclaw": {
+      "optional": true
+    }
+  },
   "devDependencies": {
     "@types/node": "^25.3.3",
     "commander": "^14.0.3",