docs(node-sdk): audit package metadata, README, AGENTS

Drop the redundant .npmignore and publish dist only; README lists every client method and the real default key id; AGENTS.md records the shared plugin and test modules.

Claude-Session: https://claude.ai/code/session_01Agoc9bRVE9KL7mmWtey9Vq

package.json

@@ -8,8 +8,7 @@
     "elydora": "dist/cli.js"
   },
   "files": [
-    "dist",
-    "scripts"
+    "dist"
   ],
   "scripts": {
     "build": "tsc && node scripts/postbuild.mjs",