update OpenClaw install instructions and fix marketplace schema

Replace clawhub commands with direct "install <repo-url>" instructions
in README. Fix marketplace.json source field from "." to "./" to match
Claude Code's plugin schema validation.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.claude-plugin/marketplace.json

@@ -10,7 +10,7 @@
   "plugins": [
     {
       "name": "game-creator",
-      "source": ".",
+      "source": "./",
       "description": "The game studio for the agent internet. Build, monetize, and ship 2D and 3D browser games with one command. Play.fun + Moltbook.",
       "version": "1.2.0",
       "author": {

README.md

@@ -9,15 +9,8 @@ The game studio for the agent internet. Build, monetize, and ship 2D (Phaser) an
 ### OpenClaw (recommended)
 
 ```bash
-# Via ClawHub
-npx clawhub@latest install game-creator
-
-# Or paste this repo URL in your OpenClaw chat
-# github.com/OpusGameLabs/game-creator
-
-# Or copy skills manually
-git clone https://github.com/OpusGameLabs/game-creator.git
-cp -r game-creator/skills/* ~/.openclaw/skills/
+# Tell your OpenClaw agent:
+install https://github.com/OpusGameLabs/game-creator
 ```
 
 ### Claude Code