docs: sentence-case sweep across 10 more pages

- tools/plugin: Package Entrypoints
- tools/code-execution: How To Use It
- tools/browser-linux-troubleshooting: Root Cause, Config Reference
- install/bun: Lifecycle Scripts
- nodes/audio: Mention Detection in Groups
- nodes/images: Inbound Media to Commands (Pi)
- platforms/android: Connection Runbook
- plugins/building-plugins: Beta Release Testing
- web/control-ui: Content Security Policy
- security/THREAT-MODEL-ATLAS: Framework Attribution

docs/tools/plugin.md

@@ -90,7 +90,7 @@ Both show up under `openclaw plugins list`. See [Plugin Bundles](/plugins/bundle
 If you are writing a native plugin, start with [Building Plugins](/plugins/building-plugins)
 and the [Plugin SDK Overview](/plugins/sdk-overview).
 
-## Package Entrypoints
+## Package entrypoints
 
 Native plugin npm packages must declare `openclaw.extensions` in `package.json`.
 Each entry must stay inside the package directory and resolve to a readable