Docs - Remove AI slop from Use Case pages

[MantisClone]

Problem

Use Case pages contain AI-generated warnings, marketing fluff, placeholder links, speculative content, and "coming soon" notices that undermine credibility and user experience.

Proposed Solution

Clean up all 6 Use Case pages (invoicing, payouts, payroll, checkout, subscriptions, payment-detection):

• Remove AI-generated warning boxes
• Replace marketing language with factual, concise copy
• Fix all placeholder # links or remove them
• Remove "coming soon" notices
• Verify all feature claims against actual codebase
• Update to accurate chain count (9, not 10)
• Replace emojis in titles with proper icons

Considerations

• Invoicing page cleanup completed as template
• Apply similar changes to remaining 5 pages
• Keep text-first approach (no videos/demos until ready)
• Maintain consistent structure across all Use Case pages
• Verify features exist before documenting them
• Balance between "bridge" content (developer-focused marketing) and pure technical docs

Progress

• ✅ Invoicing page cleaned up
• ⏳ Payouts, Payroll, Checkout, Subscriptions, Payment Detection - pending