run_eval.py: claude -p never triggers skills/commands (0% trigger rate across all queries)

## Bug Description

`run_eval.py` creates a command file in `.claude/commands/` with the skill description in YAML frontmatter, then runs `claude -p` with test queries to check if Claude invokes the `Skill` or `Read` tool for that command. In practice, **no query ever triggers the skill** — all should-trigger queries get 0/3 trigger rate, including an explicit "run /lucas:memory-layer please".

## Reproduction

Tested with 8 different skills (144 total queries across all eval sets). Every should-trigger query scored 0/3 triggers. Every should-not-trigger query also scored 0/3 (correctly, but vacuously).

Diagnostic test with maximally obvious trigger:
```json
[{"query": "I need to use the lucas memory layer skill right now, run /lucas:memory-layer please", "should_trigger": true}]
```
Result: 0/3 triggers.

## Environment
- Claude Code v2.1.71
- macOS Darwin 25.3.0
- Model: claude-opus-4-6
- Ran from external terminal (no active Claude Code session)

## Analysis

The issue appears to be that `claude -p` does not auto-trigger commands placed in `.claude/commands/` the same way an interactive Claude Code session triggers skills from `~/.claude/skills/`. Possible causes:

1. **Commands vs Skills**: Commands in `.claude/commands/` may not appear in Claude's `available_skills` list the same way skills do, or may only be invocable via explicit `/command-name` syntax
2. **`claude -p` mode**: The `-p` (pipe/prompt) mode may not load commands/skills at all, or may not present them to the model
3. **Simple query threshold**: Claude may not consult skills for queries it can handle directly — but even explicit "run this skill" failed, ruling this out as the sole cause

## Expected Behavior

At minimum, an explicit request like "run /skill-name please" should trigger the command (rate > 0/3). Description-matched queries should trigger at a reasonable rate.

## Suggested Fix

- Verify that `claude -p` actually loads and presents `.claude/commands/` files to the model
- Consider placing test skills in `~/.claude/skills/` instead of `.claude/commands/` if skills and commands are triggered differently
- Add a `--debug` flag to `run_eval.py` that dumps what Claude actually sees (system prompt, available skills list) to verify the command file is being presented