feat(opencode): add installer for AI coding assistant

opencode/README.md

@@ -0,0 +1,163 @@
+---
+title: opencode
+homepage: https://github.com/anomalyco/opencode
+tagline: |
+  opencode: The open source coding agent.
+---
+
+To update or switch versions, run `webi opencode@stable` (or `@v1.2`, `@beta`, etc).
+
+### Files
+
+These are the files / directories that are created and/or modified with this
+install:
+
+```text
+~/.config/envman/PATH.env
+~/.local/bin/opencode
+~/.local/opt/opencode-VERSION/bin/opencode
+~/.config/opencode/opencode.json
+```
+
+## Cheat Sheet
+
+> `opencode` is a terminal-based AI coding assistant. It connects to LLM
+> providers (Anthropic, OpenAI, Google, local models via Ollama) and gives you
+> an interactive TUI for writing, reviewing, and refactoring code — with full
+> tool use, file editing, and shell access.
+
+### How to Get Started
+
+1. Set an API key for your preferred provider:
+
+   ```sh
+   export ANTHROPIC_API_KEY="sk-ant-..."
+   # or
+   export OPENAI_API_KEY="sk-..."
+   ```
+
+2. Launch opencode in your project directory:
+
+   ```sh
+   cd ~/your-project
+   opencode
+   ```
+
+   opencode starts a TUI where you can chat, edit files, run commands, and
+   navigate your codebase — all from the terminal.
+
+### How to Configure Providers
+
+opencode supports multiple LLM providers simultaneously. Add them to
+`~/.config/opencode/opencode.json`:
+
+```json
+{
+  "$schema": "https://opencode.ai/config.json",
+  "provider": {
+    "anthropic": {},
+    "openai": {},
+    "google": {}
+  },
+  "model": {
+    "big": "anthropic/claude-sonnet-4-5-20250514",
+    "small": "anthropic/claude-haiku-4-5-20250514"
+  }
+}
+```
+
+Anthropic and OpenAI providers read from `ANTHROPIC_API_KEY` and
+`OPENAI_API_KEY` environment variables respectively.
+
+### How to Use with Local Models (Optional)
+
+If you prefer fully local AI coding with no API calls, you can use
+[ollama](../ollama/) (also available via webi):
+
+```sh
+# Install ollama separately (optional)
+curl https://webi.sh/ollama | sh
+source ~/.config/envman/PATH.env
+```
+
+1. Start the `ollama` server and pull a model:
+
+   ```sh
+   ollama serve &
+   ollama pull qwen2.5-coder:14b
+   ```
+
+2. Configure opencode to use the local model:
+
+   ```json
+   {
+     "$schema": "https://opencode.ai/config.json",
+     "provider": {
+       "ollama": {
+         "models": {
+           "qwen-coder": {
+             "id": "qwen2.5-coder:14b",
+             "name": "Qwen 2.5 Coder 14B"
+           }
+         }
+       }
+     },
+     "model": {
+       "big": "ollama/qwen-coder",
+       "small": "ollama/qwen-coder"
+     }
+   }
+   ```
+
+3. Launch opencode — it will connect to your local Ollama instance:
+
+   ```sh
+   opencode
+   ```
+
+### How to Use Plugins (oh-my-opencode)
+
+opencode supports plugins for multi-agent orchestration, custom tools, and
+extended workflows.
+[oh-my-opencode](https://github.com/code-yeongyu/oh-my-opencode) is a plugin
+that adds specialized agents, model routing, and skill-based delegation:
+
+1. Install the plugin:
+
+   ```sh
+   cd ~/.config/opencode
+   npm install oh-my-opencode
+   ```
+
+2. Add it to your config:
+
+   ```json
+   {
+     "$schema": "https://opencode.ai/config.json",
+     "plugin": ["oh-my-opencode"]
+   }
+   ```
+
+3. Configure agents in `~/.config/opencode/oh-my-opencode.json`:
+
+   ```json
+   {
+     "agents": {
+       "oracle": {
+         "description": "Read-only high-IQ consultant for architecture",
+         "model": "anthropic/claude-sonnet-4-5-20250514",
+         "tools": ["Read", "Grep", "Glob", "WebFetch"]
+       }
+     }
+   }
+   ```
+
+### Useful Key Bindings
+
+| Key      | Action                           |
+| -------- | -------------------------------- |
+| `Enter`  | Send message                     |
+| `Ctrl+E` | Open editor for multi-line input |
+| `Ctrl+C` | Cancel current operation         |
+| `Ctrl+L` | Clear screen                     |
+| `/`      | Slash commands                   |