[docs] Scaffold reference guides + README Documentation section

- Documentation/{Extensions,SwiftUI,UIKit}.md shells with category headings + TOC
- README: Documentation table linking all 4 guides
- footer: drop the second github badge, keep the resume link

Documentation/SwiftUI.md

@@ -0,0 +1,21 @@
+# LCEssentials — SwiftUI
+
+SwiftUI components and `View` helpers. Foundation/value-type helpers are in
+[Extensions.md](Extensions.md); UIKit-era helpers in [UIKit.md](UIKit.md).
+
+Every section is a collapsible block — click a heading to expand it.
+
+## Contents
+
+- [Navigation](#navigation)
+- [View helpers](#view-helpers)
+
+---
+
+## Navigation
+
+<!-- batch 8 -->
+
+## View helpers
+
+<!-- batch 8 -->