fix(browser): keep text/javascript API responses in network output

[jackwener]

Summary

• include JS-like API response content types in default browser network output
• keep static JS assets filtered by URL extension
• document when to use browser network --all for content-type / URL-filter diagnosis

Fixes #1172.

Verification

• npx vitest run src/cli.test.ts -t "browser network command"
• npm run typecheck