fix(olp-plugin): add openclaw.extensions field for modern OpenClaw v2026.5+ install (#62)

Discovered 2026-05-27 while bringing up Mac mini as OpenClaw client of
PI231 OLP server: `openclaw plugins install ./olp-plugin/` fails with

  package.json missing openclaw.extensions; update the plugin package to
  include openclaw.extensions (for example ["./dist/index.js"])

OpenClaw v2026.5.22 enforces a stricter plugin-manifest validation than
earlier revisions. The olp-plugin/package.json still used the legacy
schema (`type: "plugin"` + `pluginManifest`) without the new
`extensions: [./index.js]` field that modern OpenClaw requires for the
gateway plugin-discovery loop.

Workaround until this fix lands: manually `cp -R olp-plugin
~/.openclaw/extensions/olp` (symlink also works per docs Option B).

Changes:
- olp-plugin/package.json: added `extensions: ["./index.js"]` to the
  openclaw block. Keeps legacy fields (`type`, `id`, `pluginManifest`)
  for backwards compat with pre-2026.5 OpenClaw revisions; the modern
  loader only reads `extensions`.

- docs/integrations/openclaw.md:
  - § 3 Configure: rewrote example to show the modern `plugins.allow` +
    `plugins.entries.olp.{enabled, config}` schema. The previous shape
    (`plugins.olp.{proxyUrl, apiKey}` at top level) doesn't match what
    OpenClaw actually picks up.
  - § Known issues: added a paragraph documenting the
    `openclaw.extensions` schema-drift event + recovery path (pull latest
    OLP, or symlink fallback).

Verified post-fix: `openclaw plugins install ./olp-plugin/` succeeds on
Mac mini OpenClaw v2026.5.22.

Authority:
- Reproduced live on Mac mini 2026-05-27 during PI231-as-server topology
  bring-up
- OpenClaw stock plugin format (sample: `/opt/homebrew/lib/node_modules/
  openclaw/dist/extensions/anthropic/package.json` uses `extensions:
  ["./index.js"]`)

Co-authored-by: dtzp555 <dtzp555@gmail.com>
Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

olp-plugin/package.json

@@ -10,6 +10,7 @@
   "openclaw": {
     "type": "plugin",
     "id": "olp",
-    "pluginManifest": "openclaw.plugin.json"
+    "pluginManifest": "openclaw.plugin.json",
+    "extensions": ["./index.js"]
   }
 }