c3a72e026e
The TUI's CommandController special-cased backend.id === "off" for /memory stats|diagnose, but the ACP/RPC slash-command handler in builtin-registry.ts still fell back to the generic "not available for the off backend" template — non-TUI users with memory.backend=off saw the self-contradictory wording this PR was meant to remove. Extract the shared fallback into memoryStatsUnavailableMessage() (memory-backend/messages.ts) and use it from both CommandController and the ACP builtin-registry handler, so the two surfaces can't drift again. Addresses review comment: https://github.com/can1357/oh-my-pi/pull/7251#discussion_r3695383090