footer: Add a semi-flexible template system

internal/dis/component/auth/login.html

@@ -1,3 +1,20 @@
 {{ template "_form.html" . }}
 {{ define "form/title" }}Login Required{{ end }}
 {{ define "form/button" }}Login{{ end }}
+{{ define "form/inside" }}
+<div class="pure-form-group">
+    <p>
+        The site you are attempting to access requires you to login with your account.
+        Simply fill out the form below and click <em>Login</em>.
+    </p>
+    <p>
+        <small>
+            This functionality requires you to have cookies enabled.
+            A cookie to prevent fraudulent login attempts has already been set on your machine.
+            When clicking the <em>Login</em> button, a further cookie will be set on your computer to keep track of your login session.
+            If you do not wish to have futher cookie(s) set, do not click Login and do not attempt to access protected sites.
+            See also <a href="/legal/#cookies">Legal Notices</a>.
+        </small>
+    </p>
+</div>
+{{ end }}

internal/dis/component/auth/panel/panel.go

@@ -79,7 +79,7 @@ func (panel *UserPanel) UserFormContext(ctx httpx.FormContext, r *http.Request)
 	user, err := panel.Dependencies.Auth.UserOf(r)
 
 	uctx := userFormContext{FormContext: ctx}
-	panel.Dependencies.Custom.Update(&uctx)
+	panel.Dependencies.Custom.Update(&uctx, r)
 	if err == nil {
 		uctx.User = &user.User
 	}

internal/dis/component/auth/panel/totp.go

@@ -98,7 +98,7 @@ func (panel *UserPanel) routeTOTPEnroll(ctx context.Context) http.Handler {
 					FormContext: context,
 				},
 			}
-			panel.Dependencies.Custom.Update(&ctx.userFormContext)
+			panel.Dependencies.Custom.Update(&ctx.userFormContext, r)
 
 			if err == nil && user != nil {
 				ctx.userFormContext.User = &user.User

internal/dis/component/auth/panel/user.go

@@ -28,9 +28,9 @@ func (panel *UserPanel) routeUser(ctx context.Context) http.Handler {
 	userTemplate := panel.Dependencies.Custom.Template(userTemplate)
 	return &httpx.HTMLHandler[routeUserContext]{
 		Handler: func(r *http.Request) (ruc routeUserContext, err error) {
-			panel.Dependencies.Custom.Update(&ruc)
+			panel.Dependencies.Custom.Update(&ruc, r)
 			ruc.AuthUser, err = panel.Dependencies.Auth.UserOf(r)
-			return routeUserContext{}, err
+			return ruc, err
 		},
 		Template: userTemplate,
 	}

internal/dis/component/auth/session.go

@@ -125,7 +125,7 @@ func (auth *Auth) authLogin(ctx context.Context) http.Handler {
 			if context.Err != nil {
 				context.Err = errLoginFailed
 			}
-			httpx.WriteHTML(auth.Dependencies.Custom.NewForm(context), nil, loginTemplate, "", w, r)
+			httpx.WriteHTML(auth.Dependencies.Custom.NewForm(context, r), nil, loginTemplate, "", w, r)
 		},
 
 		Validate: func(r *http.Request, values map[string]string) (*AuthUser, error) {