Add developer guide and normalize doc links Add comprehensive developer guide (guide.md) covering quick start, grid snapping, constraints, animations, UI controls, tooltips, styles, settings API, and FAQs. Normalize internal markdown links throughout documentation by removing .md extensions from link targets, improving portability across different documentation systems.
Add WindowUtils documentation suite Add comprehensive markdown docs for WindowUtils modules, covering the API, controls, bind system, splitter layouts, notifications, tutorials, and related helpers.