docs: update config to use npm package, highlight Codex Max in changelog

- Changed config/full-opencode.json plugin from local file path to npm package name
- Added Highlights section to v4.0.0 changelog emphasizing Codex Max support

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: numman-ali

CHANGELOG.md

@@ -4,7 +4,12 @@ All notable changes to this project are documented here. Dates use the ISO forma
 
 ## [4.0.0] - 2025-11-25
 
-**Major release**: Complete prompt engineering overhaul matching official Codex CLI behavior.
+**Major release**: Complete prompt engineering overhaul matching official Codex CLI behavior, with full **GPT-5.1 Codex Max** support.
+
+### Highlights
+- **Full Codex Max support** with dedicated prompt including frontend design guidelines
+- **Model-specific prompts** matching Codex CLI's prompt selection logic
+- **GPT-5.0 → GPT-5.1 migration** as legacy models are phased out
 
 ### Added
 - **Model-specific system prompts**: Plugin now fetches the correct Codex prompt based on model family, matching Codex CLI's `model_family.rs` logic:

config/full-opencode.json

@@ -1,7 +1,7 @@
 {
   "$schema": "https://opencode.ai/config.json",
   "plugin": [
-    "file:///Users/numman/Repos/opencode-codex-plugin-fresh/dist"
+    "opencode-openai-codex-auth"
   ],
   "provider": {
     "openai": {