feat: add configuration options for instagram and twitter plugins

CLAUDE.md

@@ -10,6 +10,11 @@ When creating, modifying, or removing plugins:
    - Brief description of functionality
    - Usage instructions with examples
    - Any configuration requirements
+3. **For plugins with configuration options:**
+   - Set `ConfigRequired: true` in the plugin's BasePlugin struct
+   - Add corresponding HTML form fields in `internal/admin/templates/channel_plugin_config.html`
+   - Use conditional template logic: `{{else if eq .ChannelPlugin.PluginID "plugin.id"}}`
+   - Include proper form labels, help text, and value binding
 
 ## Testing