feat(cli): add version check to agentv studio/serve commands

[christso]

Problem

agentv eval checks required_version from .agentv/config.yaml and prompts the user to update if there's a mismatch (#1125, merged in #1126). However, agentv studio and agentv serve do not perform this check — they launch silently even if the installed version doesn't satisfy the project's requirement.

Desired behavior

When agentv studio or agentv serve is run in a repo with .agentv/config.yaml containing required_version:

• Interactive (TTY): Same "Update now? (Y/n)" prompt as agentv eval
• Non-interactive: Warn to stderr, continue

This covers the primary use case: a developer running Studio locally in a single project.

Scope

• Single-project local runs only
• Multi-project server deployments (one agentv serving multiple repos with different version requirements) are out of scope — that needs per-project local installs (see feat(cli): self update should update the same binary location (local vs global) #1127)

Files to change

• apps/cli/src/commands/results/serve.ts — add enforceRequiredVersion() call before starting the server, similar to run-eval.ts:988-992

Related

• feat(cli): Auto-update when version mismatch detected #1125 / feat(cli): auto-update when version mismatch detected #1126 — auto-update on version mismatch (eval command)
• feat(cli): self update should update the same binary location (local vs global) #1127 — local vs global install detection