feat: add Keycloak authentication for dashboard and API endpoints (#2)

Dashboard: OAuth2/OIDC login flow with PKCE, session-based auth middleware
protecting all server function endpoints, check-auth server function for
frontend auth state, login page gate in AppShell, user info in sidebar.

Agent API: JWT validation middleware using Keycloak JWKS endpoint,
conditionally enabled when KEYCLOAK_URL and KEYCLOAK_REALM are set.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Co-authored-by: Sharang Parnerkar <parnerkarsharang@gmail.com>
Reviewed-on: #2

compliance-dashboard/src/components/sidebar.rs

@@ -1,3 +1,4 @@
+use compliance_core::models::auth::AuthInfo;
 use dioxus::prelude::*;
 use dioxus_free_icons::icons::bs_icons::*;
 use dioxus_free_icons::Icon;
@@ -114,8 +115,32 @@ pub fn Sidebar() -> Element {
                     Icon { icon: BsChevronLeft, width: 14, height: 14 }
                 }
             }
-            if !collapsed() {
-                div { class: "sidebar-footer", "v0.1.0" }
+            {
+                let auth_info = use_context::<Signal<AuthInfo>>();
+                let info = auth_info();
+                let initials = info.name.chars().next().unwrap_or('U').to_uppercase().to_string();
+                rsx! {
+                    div { class: "sidebar-user",
+                        div { class: "user-avatar",
+                            if info.avatar_url.is_empty() {
+                                span { class: "avatar-initials", "{initials}" }
+                            } else {
+                                img { src: "{info.avatar_url}", alt: "avatar", class: "avatar-img" }
+                            }
+                        }
+                        if !collapsed() {
+                            div { class: "user-info",
+                                span { class: "user-name", "{info.name}" }
+                                a {
+                                    href: "/logout",
+                                    class: "logout-link",
+                                    Icon { icon: BsBoxArrowRight, width: 14, height: 14 }
+                                    " Logout"
+                                }
+                            }
+                        }
+                    }
+                }
             }
         }
     }