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>

auth/types.go

@@ -0,0 +1,30 @@
+package auth
+
+// OIDCConfig holds the OIDC provider configuration
+type OIDCConfig struct {
+	Issuer        string `json:"issuer"`
+	AuthURL       string `json:"authorization_endpoint"`
+	TokenURL      string `json:"token_endpoint"`
+	UserInfoURL   string `json:"userinfo_endpoint"`
+	JWKSURL       string `json:"jwks_uri"`
+	ScopesSupported []string `json:"scopes_supported"`
+}
+
+// TokenResponse represents the response from token exchange
+type TokenResponse struct {
+	AccessToken  string `json:"access_token"`
+	IDToken      string `json:"id_token"`
+	RefreshToken string `json:"refresh_token"`
+	TokenType    string `json:"token_type"`
+	ExpiresIn    int    `json:"expires_in"`
+}
+
+// UserInfo represents user information from the OIDC provider
+type UserInfo struct {
+	Sub               string `json:"sub"`
+	Email             string `json:"email"`
+	EmailVerified     bool   `json:"email_verified"`
+	Name              string `json:"name"`
+	PreferredUsername string `json:"preferred_username"`
+	Groups            []string `json:"groups,omitempty"`
+}