feat(web): two-stage questionnaires, screening result and diary by result

- Sign-in: centred ЕМИАС card without the sidebar; anonymous entry asks «Депрессия / ПТСР».
- Stage 1 is the same for everyone and follows the fixed order of the MVP questionnaire:
  PHQ-2 → trauma filter/TSQ → RUS-AUDIT-S → C-SSRS → context; stage 2 only where stage 1
  is positive. Starts without a profile.
- After stage 1 the patient sees a preliminary result (screening, not a diagnosis), stored
  with the record; it switches on the diary modules (depression / PTSD).
- Stage 2 diary: morning (sleep, sleep quality, alcohol) and evening (mood, medication,
  3 PHQ-9 items in rotation, short PCL-5); C-SSRS since last contact only under risk;
  flags on weekly means against the personal norm; scheduled full scales with change
  (remission, response, worsening).
- Questionnaire log: GET /me/{token}/results and the «Мои результаты» screen.
- Questionnaires centred without the sidebar and without scale names; «Продолжить позже»
  goes home; confirmations are toasts; free-text comments are optional.
- Demo policy config/questionnaire_demo.yaml (INTAKE_DEMO only, not a clinical approval).

ADR-012.

Refs #77

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/components/Toast.tsx

@@ -0,0 +1,55 @@
+import { createContext, useCallback, useContext, useMemo, useRef, useState, type ReactNode } from "react";
+
+import { Icon } from "./Icon";
+
+/*
+ * Short confirmations («отметил приём», «дневник сохранён») as a toast in the top-right corner instead of a separate
+ * confirmation page: the person lands on the home screen right away and still sees what happened.
+ */
+
+interface Toast {
+  id: number;
+  text: string;
+}
+
+const Ctx = createContext<(text: string) => void>(() => undefined);
+const LIFETIME_MS = 6000;
+
+export function ToastProvider({ children }: { children: ReactNode }) {
+  const [toasts, setToasts] = useState<Toast[]>([]);
+  const next = useRef(0);
+
+  const close = useCallback((id: number) => setToasts((all) => all.filter((t) => t.id !== id)), []);
+  const show = useCallback(
+    (text: string) => {
+      const id = ++next.current;
+      setToasts((all) => [...all.slice(-2), { id, text }]);
+      window.setTimeout(() => close(id), LIFETIME_MS);
+    },
+    [close],
+  );
+
+  const value = useMemo(() => show, [show]);
+  return (
+    <Ctx.Provider value={value}>
+      {children}
+      <div className="toasts" role="status" aria-live="polite">
+        {toasts.map((t) => (
+          <div key={t.id} className="toast">
+            <span className="toast__icon" aria-hidden="true">
+              <Icon name="check" size={18} />
+            </span>
+            <p className="toast__text">{t.text}</p>
+            <button type="button" className="toast__close" onClick={() => close(t.id)} aria-label="Закрыть">
+              <Icon name="close" size={18} />
+            </button>
+          </div>
+        ))}
+      </div>
+    </Ctx.Provider>
+  );
+}
+
+export function useToast(): (text: string) => void {
+  return useContext(Ctx);
+}