Document the Tab double-processing bug and its solution:
- Symptom: Row color alternating on Tab press
- Root cause: Tab processed twice (widget + app level)
- Solution: NavigateDirection + handled flag + app check
- General rule for keyboard handling in immediate-mode widgets
Also updated EditKeyboardResult API documentation with new fields.
Complete documentation covering:
- When to use AdvancedTable vs VirtualAdvancedTable
- Architecture diagram (table_core.zig as single source)
- How to extend functionality (always in table_core.zig)
- Complete API reference for table_core.zig
- Code examples and model differences
