review: tell users to update a Claude Code too old for isolated reviews

The reviewer depends on --setting-sources, --settings, and --strict-mcp-config. A Claude Code without them (1.0.x) exits with a bare "unknown option" before loading anything, so the review fails closed but names no remedy. ReviewerTemplate gains an optional ClassifyExit hook, and the Claude reviewer uses it to say which flag is missing and to update.

Also document what those flags keep out, checked on Claude Code 2.0.0 through 2.1.286: the checkout's commands, skills, and agents are not discovered, and CLAUDE.md is not preloaded. That is why the previous commit's command-change check is reverted: no version it could protect loads checkout commands under these flags.