feat: support directory paths in eval run command

[christso]

Summary

`agentv eval run evals/hivespec/` fails — must use `"evals/hivespec/*.eval.yaml"` glob. This is a usability issue that agents hit when trying to run all evals for a plugin.

Current behavior

```bash

Fails with "No eval files matched"

agentv eval run --target pi-cli evals/hivespec/

Works

agentv eval run --target pi-cli "evals/hivespec/*.eval.yaml"
```

Expected behavior

```bash

Should work — auto-expand to evals/hivespec/**/*.eval.yaml

agentv eval run --target pi-cli evals/hivespec/
```

Implementation

In `apps/cli/src/commands/eval/commands/run.ts`, when a path argument is a directory, automatically expand it to `

/**/*.eval.yaml`.

Acceptance signals

• `agentv eval run evals/hivespec/` works (expands to glob)
• `agentv eval run evals/hivespec` works (without trailing slash)
• Existing glob patterns still work unchanged
• Error message when directory contains no eval files

Non-goals

• Recursive search for non-.eval.yaml files