- Add comprehensive Echo v5 migration guide (ECHO_V5_MIGRATION.md)
- Documents all API changes and type signature updates
- Provides step-by-step fixes for deprecated middleware
- Includes middleware pattern examples for v5
- Documents WebSocket fix for v5 compatibility
- Includes verification and rollback plans
- Remove outdated infrastructure enhancement plan (3488 lines)
- Legacy plan is no longer relevant after Echo v5 migration
- Consolidates documentation into single migration guide
