Initial iris repository structure

WASM reactive UI framework for Go:
- reactive/ - Signal[T], Effect, Runtime
- ui/ - Button, Text, Input, View, Canvas, SVG components
- navigation/ - Router, guards, history management
- auth/ - OIDC client for WASM applications
- host/ - Static file server

Extracted from arcadia as open-source component.

Co-Authored-By: Claude <noreply@anthropic.com>

ui/app_router.go

@@ -0,0 +1,29 @@
+package ui
+
+import (
+	"git.flowmade.one/flowmade-one/iris/internal/element"
+	"git.flowmade.one/flowmade-one/iris/reactive"
+)
+
+// Router interface to avoid import cycle
+type Router interface {
+	GetCurrentView() View
+}
+
+// NewAppWithRouter creates a new app with navigation support
+func NewAppWithRouter(router Router) {
+	app := NewView()
+	app.e.Grid()
+	app.MinHeight("100vh")
+	
+	// Create a reactive view that updates when routes change
+	reactive.NewEffect(func() {
+		currentView := router.GetCurrentView()
+		// Clear the app and add the current view
+		// Note: In a production implementation, we'd want better DOM diffing
+		app.e.Set("innerHTML", "")
+		app.Child(currentView)
+	})
+	
+	element.Mount(app.e)
+}