refactor: migrate pi-subagents to tintinweb, pi-tasks replaces rpiv-todo. Updated subagents reference from nicobailon/pi-subagents to tintinweb/pi-subagents (Agent() tool, inherit_context: false = fresh by default). Replaced @juicesharp/rpiv-todo with @tintinweb/pi-tasks (TaskCreate/TaskList/TaskUpdate). Install scripts (install.sh, setup.sh) updated to install new packages. Updated README dependencies table and capabilities matrix. references/cli-tools/subagents.md and todo.md rewritten with both extensions documented; cali-* skill copies are auto-synced via sync-cli-tools.sh.