Add configure tool target picker

[doedja]

What changed

• Ask which tool to configure when Claude Code and Codex are both detected.
• Offer Claude Code, Codex CLI, and Both, with Both as the default.
• Select the only detected tool automatically.
• Require non-interactive callers to name Claude or Codex.
• Print one combined routing summary before an atomic save.
• Release the flow as @kenarihq/cli@0.4.0.

Why

Running kenari configure previously started the Claude flow immediately and configured every detected tool in registry order. On systems with both tools, that looked like a hidden Claude default and gave users no target choice.

Checks

• npm test, 88 passing
• Target picker choice matrix
• Single-tool prompt bypass
• Non-interactive explicit-target check
• Real TTY menu with Both as the Enter default
• npm pack --dry-run --json
• git diff --check