refactor: move platform config directories to repo root for discovery

Move .codex/, .opencode/, .openclaw/ from understand-anything-plugin/ to
repo root so each AI coding platform discovers its config at the standard
location. Delete .cursor/ (replaced by .cursor-plugin/plugin.json in next
commit). Plugin source code stays inside understand-anything-plugin/.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.opencode/INSTALL.md

@@ -0,0 +1,37 @@
+# Installing Understand-Anything for OpenCode
+
+## Prerequisites
+
+- [OpenCode.ai](https://opencode.ai) installed
+
+## Installation
+
+Add understand-anything to the `plugin` array in your `opencode.json` (global or project-level):
+
+```json
+{
+  "plugin": ["understand-anything@git+https://github.com/Lum1104/Understand-Anything.git"]
+}
+```
+
+Restart OpenCode. The plugin auto-installs and registers all skills.
+
+## Verify
+
+Ask: "List available skills" — you should see understand, understand-chat, understand-dashboard, etc.
+
+## Usage
+
+```
+use skill tool to load understand-anything/understand
+```
+
+Or just ask: "Analyze this codebase and build a knowledge graph"
+
+## Updating
+
+Restart OpenCode — the plugin re-installs from git automatically.
+
+## Uninstalling
+
+Remove the plugin line from `opencode.json` and restart.