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>

.codex/INSTALL.md

@@ -0,0 +1,55 @@
+# Installing Understand-Anything for Codex
+
+## Prerequisites
+
+- Git
+
+## Installation
+
+1. **Clone the repository:**
+   ```bash
+   git clone https://github.com/Lum1104/Understand-Anything.git ~/.codex/understand-anything
+   ```
+
+2. **Create the skills symlink:**
+   ```bash
+   mkdir -p ~/.agents/skills
+   ln -s ~/.codex/understand-anything/understand-anything-plugin/skills ~/.agents/skills/understand-anything
+   ```
+
+   **Windows (PowerShell):**
+   ```powershell
+   New-Item -ItemType Directory -Force -Path "$env:USERPROFILE\.agents\skills"
+   cmd /c mklink /J "$env:USERPROFILE\.agents\skills\understand-anything" "$env:USERPROFILE\.codex\understand-anything\understand-anything-plugin\skills"
+   ```
+
+3. **Restart Codex** to discover the skills.
+
+## Verify
+
+```bash
+ls -la ~/.agents/skills/understand-anything
+```
+
+You should see a symlink pointing to the skills directory.
+
+## Usage
+
+Skills activate automatically when relevant. You can also invoke directly:
+- "Analyze this codebase and build a knowledge graph"
+- "Help me understand this project's architecture"
+
+## Updating
+
+```bash
+cd ~/.codex/understand-anything && git pull
+```
+
+Skills update instantly through the symlink.
+
+## Uninstalling
+
+```bash
+rm ~/.agents/skills/understand-anything
+rm -rf ~/.codex/understand-anything
+```