Overhaul Feynman harness: streamline agents, prompts, and extensions

Remove legacy chains, skills, and config modules. Add citation agent,
SYSTEM.md, modular research-tools extension, and web-access layer.
Add ralph-wiggum to Pi package stack for long-running loops.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

package.json

@@ -11,11 +11,11 @@
     "dist/",
     ".pi/agents/",
     ".pi/settings.json",
+    ".pi/SYSTEM.md",
     ".pi/themes/",
     "extensions/",
     "prompts/",
     "scripts/",
-    "skills/",
     "README.md",
     ".env.example"
   ],
@@ -38,9 +38,6 @@
     "extensions": [
       "./extensions"
     ],
-    "skills": [
-      "./skills"
-    ],
     "prompts": [
       "./prompts"
     ]