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/browser-linux-troubleshooting.md

@@ -12,7 +12,7 @@ OpenClaw's browser control server fails to launch Chrome/Brave/Edge/Chromium wit
 {"error":"Error: Failed to start Chrome CDP on port 18800 for profile \"openclaw\"."}
 ```
 
-### Root Cause
+### Root cause
 
 On Ubuntu (and many Linux distros), the default Chromium installation is a **snap package**. Snap's AppArmor confinement interferes with how OpenClaw spawns and monitors the browser process.
 
@@ -123,7 +123,7 @@ curl -s -X POST http://127.0.0.1:18791/start
 curl -s http://127.0.0.1:18791/tabs
 ```
 
-### Config Reference
+### Config reference
 
 | Option                           | Description                                                          | Default                                                     |
 | -------------------------------- | -------------------------------------------------------------------- | ----------------------------------------------------------- |