fix(validation): naming pattern doesn't accommodate convert-X-Y skills

## Summary

The `validate-skill` justfile recipe uses a naming pattern that doesn't accommodate `convert-X-Y` skills, causing 78 skills to fail validation incorrectly.

## Current Pattern

```regex
^[a-z0-9]+-([a-z0-9]+-)?[a-z0-9]+-[a-z]+$
```

Expects: `-[-]-`

## Problem

`convert-X-Y` skills follow: `convert--` (no focus suffix)

This is intentional per the skill organization strategy - conversion skills don't need a focus suffix.

## Affected Skills

78 conversion skills including:
- convert-python-rust
- convert-typescript-golang
- convert-elixir-haskell
- ... (see `ls components/skills/convert-*/`)

## Proposed Fix

Update the regex in `justfile:430` to also match conversion skill pattern:

```bash
# Match standard pattern OR conversion pattern
if ! echo "$name" | grep -qE '^[a-z0-9]+-([a-z0-9]+-)?[a-z0-9]+-[a-z]+$|^convert-[a-z]+-[a-z]+$'; then
```

## Impact

- 78 skills currently marked as "failed" when they're valid
- `validate-all-skills` reports 89 failures instead of ~11