chore: move skills and evals to plugins/bin, remove legacy root configs

Skills and evals migrated from .agents/ to plugins/bin/ plugin directory.
Remove .mcp.json, provider-manifest.sh, and skills-lock.json legacy artifacts.

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

.github/plugin/marketplace.json

@@ -8,6 +8,11 @@
       "name": "kyberforge",
       "description": "Skills and agents for creating, maintaining, and managing a Claude Code / Copilot CLI plugin marketplace.",
       "source": "./plugins/kyberforge"
+    },
+    {
+      "name": "bin",
+      "description": "A place for things to be binned",
+      "source": "./plugins/bin"
     }
   ]
 }