docs: README polish — value prop, demo GIF, feature comparison table

[ajianaz]

What

Polish README.md: crystal clear value prop, demo GIF, one-command Docker deploy, honest feature comparison table.

Why

BMAD CMO finding: README is the first thing people see. It must communicate:

1. What TrapFall is (1 sentence)
2. Why use it over Sentry/GlitchTip (positioning)
3. How to try it in 60 seconds (one-command Docker)
4. What works and what doesn't (honesty builds trust)

Changes

1. Hero section: 1-sentence pitch + badges (version, license, Docker size, stars)
2. Demo GIF: 10-15 second loop showing error capture → dashboard → MCP query
3. Quick Start:

   docker run -p 9090:9090 ghcr.io/codecoradev/trapfall:latest
   

4. Feature comparison table:

   Feature	TrapFall	Sentry	GlitchTip
   Self-hosted	✅	⚠️ Heavy	✅
   MCP tools	✅ 12	❌	❌
   Docker size	6MB	~500MB+	~400MB+
   Sentry SDK compat	✅	Native	✅
   Performance tracing	✅	✅	Limited
   Cloud tier	❌	✅	✅

5. MCP section: "Your AI agent can query production errors" + quick example
6. Honest limitations: "No SSO yet, no cloud tier, new project — but actively developed"

Testing

• Fresh-eyes review: would a new user understand TrapFall in 30 seconds?
• All links work
• Docker command tested and works