Plugin development guide for Heratio

<p>For developers interested in building Heratio plugins, here are the key conventions:</p><ul><li>Plugin naming: ahg[DescriptiveName]Plugin</li><li>Use Laravel Query Builder (not raw PDO)</li><li>Include install.sql in database/ folder</li><li>Use namespaced classes where possible</li><li>Support CSP nonces in all templates</li></ul><p>Full documentation is being prepared. In the meantime, feel free to ask questions here.</p>