feat(sideshow-term): auto-start server for watcher

[benvinegar]

Summary

• Make bare sideshow-term open the TUI watcher
• Make sideshow-term watch auto-start a local server when no server is reachable
• Default the terminal server/viewer to localhost:4243 and support --port for bare/watch commands
• Add watcher flags for --url, --no-serve, and --keep-server
• Log auto-started server output under ~/.sideshow-term/logs/ and clean up the owned server when the watcher exits

Validation

• node --check bin/sideshow-term.js
• npm test
• npm run test:render
• npm run build
• node bin/sideshow-term.js --port 44273 --no-serve
• npx oxfmt --write ... / formatted changed files

This PR description was generated by Pi using OpenAI GPT-5