Subagent and isolated cron sessions only loaded AGENTS.md and TOOLS.md,
causing subagents to lose their role personality, identity, and user
preferences. Expand MINIMAL_BOOTSTRAP_ALLOWLIST to include the three
missing identity files.
Closes#24852
(cherry picked from commit c33377150eeddb42c2a24f4a48c2d01b5cdf8d3e)