Fix postinstall patches for hoisted dependencies, add CI publish workflow

- Postinstall now walks up to find node_modules (works when deps are hoisted)
- All patches verified: piConfig, process.title, OAuth page, editor theme
- Add GitHub Actions workflow to publish on version bump

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

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@companion-ai/feynman",
-  "version": "0.2.3",
+  "version": "0.2.4",
   "description": "Research-first CLI agent built on Pi and alphaXiv",
   "type": "module",
   "bin": {