Claude Code System Prompts

@internal The server-configured session indicator (bootstrap client_data.footer_indicator) that the terminal renders as a "◆ <text>" pill in the prompt footer — an opaque status note operators set per cohort (e.g. to prove a test config reached the session). Carried on system/init and the initialize response so a host UI (Claude Desktop, IDE webviews) can render the same pill. Absent when nothing is configured; hosts should then render nothing. Read from the CLI's cached bootstrap data, so a label configured after that cache was last written first appears on a later system/init.