feat(cli): auto-update when version mismatch detected

[christso]

Summary

• Replaces "Continue anyway?" prompt with "Update now? (Y/n)" when required_version doesn't satisfy the installed version
• Y → runs self-update inline using the config's version range (e.g., agentv@">=4.1.0 <5.0.0" instead of @latest), preventing unintended major-version jumps, then exits with a re-run message
• N → continues the command without interruption (no second prompt)
• Non-interactive and --strict behavior unchanged
• Extracts shared update logic into self-update.ts so both the version check and agentv self update reuse the same code

Test plan

• Interactive: version mismatch prompts "Update now? (Y/n)" (single prompt)
• Y runs the update inline (npm or bun, auto-detected) using the config range, capped at current major (>=4.21.0 <5.0.0)
• After failed update, prints actionable fallback message ("Run agentv self update manually")
• N continues the command without interruption (eval proceeds immediately)
• Non-interactive behavior unchanged (warn + continue, no prompt)
• --strict behavior unchanged (warn + abort with upgrade hint)
• agentv self update still works independently (uses @latest)
• All 2,230 existing tests pass (1686 core + 67 eval + 477 cli)

E2E evidence

Interactive — decline update (N)

Warning: This project requires agentv >=99.0.0 but you have 4.20.0.
? Update now? (Y/n) n
✔ Update now? No
Artifact directory: ...  ← eval continues

Interactive — accept update (Y) with major-version cap

Warning: This project requires agentv >=4.21.0 but you have 4.20.0.
? Update now? (Y/n) y
✔ Update now? Yes
npm ERR! notarget No matching version found for agentv@>=4.21.0 <5.0.0.
Update failed. Run `agentv self update` manually.

Confirms: version range >=4.21.0 <5.0.0 is correctly capped at current major (4.x).

Strict mode

Warning: This project requires agentv >=99.0.0 but you have 4.20.0.
  Run `agentv self update` to upgrade.
Aborting: --strict mode requires the installed version to satisfy the required range.

Non-interactive

Warning: This project requires agentv >=99.0.0 but you have 4.20.0.
  Run `agentv self update` to upgrade.
Artifact directory: ...  ← eval continues

Self update command

$ agentv self update --help
agentv self update
> Update agentv to the latest version
FLAGS:
  --npm, --bun, --help

Closes #1125

🤖 Generated with Claude Code

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