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>

plugins/bin/plugin.json

@@ -0,0 +1,9 @@
+{
+  "name": "bin",
+  "description": "A place for things to be binned",
+  "author": { "name": "Defame1297", "email": "defame1297@rkdr.net" },
+  "license": "MIT",
+  "keywords": [],
+  "agents": "agents/",
+  "skills": ["skills/"]
+}