chore: Remove tuto-like new Class/Object documentation
chore: Major cleanup on the documentation
- Migration page
- Syntax sweeps `do x; → do x();`, & co.
- Database recipe: rewrote all four insert usages
- New dataframe page
- Fix Broken links
- Five pages were corrupted by the Phase 1 transformation commit
Rename version from 2026-0.0 to 2026-06 across all documentation
Phase 8: Class/object tutorials in LearnGAMLStepByStep
- Add ClassDefinition.md — main TOC page with concepts overview and class vs species comparison
- Add ClassDefinition_step1.md — definition & instantiation, constructor syntax, dot notation
- Add ClassDefinition_step2.md — attributes & actions, mutations, chained calls, bank account example
- Add ClassDefinition_step3.md — inheritance, parent:, super, invoke, is operator, polymorphism
- Add ClassDefinition_step4.md — virtual classes, abstract actions, partially abstract, multi-level hierarchy
- Add ClassDefinition_step5.md — advanced: objects as agent attributes, inter-agent passing, maps, identity
- Update _Sidebar.md — Classes & Objects section (items 1-5) added under LearnGAMLStepByStep