v3.8.1: update CHANGELOG.md + README.md with codebuff docs

CHANGELOG.md

@@ -1,5 +1,46 @@
 # Changelog
 
+## v3.8.1 (2026-05-24)
+
+**Codebuff Integration — FREE DeepSeek V4 Pro Access + Provider Presets Restored**
+
+### Codebuff Backend (New)
+- **`codebuff` backend type** added to `translate-proxy.py`
+- Connects to `https://codebuff.com` for free AI model access
+- **Free models available**: DeepSeek V4 Pro, DeepSeek V4 Flash, Kimi K2.6, MiniMax M2.7
+- **Agent run lifecycle management**: auto-starts/finishes agent runs per request
+- **Credential detection**: reads session token from `~/.config/manicode/credentials.json`
+- **Model-to-agent routing**: maps each model to its correct codebuff agent ID
+  - `deepseek/deepseek-v4-pro` → `base2-free-deepseek`
+  - `deepseek/deepseek-v4-flash` → `base2-free-deepseek-flash`
+  - `moonshotai/kimi-k2.6` → `base2-free-kimi`
+  - `minimax/minimax-m2.7` → `base2-free`
+
+### Setup for Codebuff
+1. `npm install -g codebuff` (already installed on system)
+2. `codebuff login` (opens browser for GitHub OAuth)
+3. Select "Codebuff (Free DeepSeek/Kimi)" preset in Codex Launcher GUI
+4. Pick a model and start coding — no API key needed!
+
+### Provider Presets Restored
+- All 17+ provider presets restored to `endpoints.json`
+- Previous issue: endpoints.json was overwritten with only 4 AG X entries
+- Restored: Command Code, Crof.ai, OpenAdapter, OpenAdapter GO Plan, OpenCode Zen (OpenAI + Anthropic), OpenCode Go (OpenAI + Anthropic), OpenRouter, NVIDIA NIM, Z.ai Coding, Google Gemini (API Key + OAuth), Google Antigravity (OAuth), Anthropic, OpenAI, Cobra (chats-llm.com)
+
+### GUI Changes
+- New preset: **"Codebuff (Free DeepSeek/Kimi)"** in provider dropdown
+- New backend type: **"Codebuff - Free DeepSeek/Kimi"** in type selector
+- Version label updated to v3.8.1
+- Changelog entry for v3.8.1 added
+
+### Stats
+- translate-proxy.py: +205 lines (codebuff backend)
+- codex-launcher-gui: +19 lines (preset + changelog)
+- .deb size: 84KB
+- Self-tests: 54/54 passing
+
+---
+
 ## v3.8.0 (2026-05-22)
 
 **AI Monitoring — Self-Healing Watchdog with 3-Tier Response System**