fix(cli): clarify index update guidance

[srobinson]

Summary

• describe version mismatches as an index update requirement
• direct users to the automatic mdm index rebuild path
• replace destructive deletion guidance for unreadable index data with recoverable rebuild guidance

Test plan

• Existing error handler suite passes: 39 tests
• pnpm build
• Biome check for src/cli/error-handler.ts
• Manual CLI version mismatch renders the new guidance