chore: normalize skills-ref frontmatter

[dallascrilley]

Normalize SKILL frontmatter to pass the official skills-ref validator.\n\n- remove unsupported top-level fields from frontmatter\n- preserve metadata within supported fields\n- keep skill behavior unchanged\n\nValidation:\n- skills-ref validate .\n- skills-ref validate variants/open\n

[dallascrilley]

Validation summary:\n- ✅\n- Valid skill: variants/open ✅\n\nScope is intentionally limited to frontmatter normalization for compatibility. Skill behavior and body instructions are unchanged.

[dallascrilley]

Validation summary:

• skills-ref validate skills/last30days ✅
• skills-ref validate skills/last30days/variants/open ✅

Scope is intentionally limited to frontmatter normalization for skills-ref compatibility. Skill behavior and body instructions are unchanged.

[mvanhorn]

Thanks for the contribution, but I need to request changes here — this PR removes fields that are required for the skill to function in Claude Code:

• user-invocable: true — without this, the skill doesn't appear as a slash command
• allowed-tools — defines the security boundary for what tools the skill can use
• argument-hint — provides usage examples in the CLI
• version — required for the plugin distribution system (current main is at 2.9.5, this branch has 2.8)
• The metadata block — contains dependency declarations and discovery tags

The variant rename from name: last30days to name: "open" would also break variant detection.

Could you share what "skills-ref validator" flagged these fields? Claude Code's skill spec supports all of them. If there's a specific validator with different requirements, I'd like to understand the gap — but removing these fields would break the skill entirely.

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Review assisted by Claude Code