Remove redundant package installer — let Pi handle it at runtime

Pi's own package manager already installs packages from settings.json
on first REPL launch. Feynman was duplicating this in both postinstall
and first-run, causing slow installs and looping.

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

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@companion-ai/feynman",
-  "version": "0.2.1",
+  "version": "0.2.2",
   "description": "Research-first CLI agent built on Pi and alphaXiv",
   "type": "module",
   "bin": {