docs: Rework remote browser page with three focused examples

- Add Note distinguishing remote vs local browser (computer use)
- Restructure into three card-linked examples: screenshot endpoints,
  agent data extraction, live browser preview
- Fix all examples so Kernel code runs inside the sandbox, not the orchestrator
- Add CodeGroup tabs (Python + JS) throughout
- Remove MCP tools table, Kernel skills section, and LLM chooser
- Add live view example with iframe embedding and read-only mode

Author: beran-t