M4I06: M4 docs + final docs sweep

[s2x]

What to do

• Full spec review: every section matches implementation
• Full plan review: all tasks marked complete/updated
• Watpliwosci review: all decisions verified, remaining open questions documented
• Create docs/superpowers/README.md with:
  • Project overview
  • Quick start (fluent API and config-based)
  • Architecture diagram (text-based from spec)
  • Link to all reference docs
• Update main project README.md with ForkliftServer section
• Create CHANGELOG.md entry for the new ForkliftServer
• Verify backward compat: all old tests still pass

Acceptance criteria

• All docs consistent with implementation
• README has quick start guide
• CHANGELOG has entry
• Old tests still pass (backward compat verified)

References

• Milestone doc: docs/superpowers/milestone-4/06-docs-examples.md