feat: refactor 30+ skills to Anthropic progressive disclosure pattern

- All SKILL.md files now <500 lines (avg reduction 69%)
- Detailed content extracted to references/ subdirectories
- Frontmatter standardised: only name + description (Anthropic standard)
- New skills: brand-guidelines, spec-coauthor, report-templates, skill-creator
- Design skills: anti-slop guidelines, premium-proposals reference
- Removed non-standard frontmatter fields (triggers, version, author, category)

Plugins affected: infraestrutura, marketing, dev-tools, crm-ops, gestao,
core-tools, negocio, perfex-dev, wordpress, design-media

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

crm-ops/skills/billing-check/SKILL.md

@@ -1,14 +1,6 @@
 ---
 name: billing-check
-description: Billing verification and invoice validation. Checks billing accuracy,
-  matches invoices with contracts. Use when user mentions "billing check", "invoice
-  verification", "billing audit", "payment verification", "billing validation".
-author: Descomplicar® Crescimento Digital
-version: 2.0.0
-quality_score: 75
-user_invocable: true
-desk_task: 1464
-allowed-tools: ToolSearch
+description: Verificação de facturação e validação de facturas. Sincroniza facturas Moloni com horas Desk CRM para projectos 360, compara horas facturadas vs entregues e calcula saldos.
 ---
 
 # Billing Check - Desk vs Moloni (v2.0)