feat(notifications): центр уведомлений о системных событиях

Добавлена система уведомлений о системных и фоновых событиях (новые записи
журнала, обработка фото, авто-проверка текста, блокировки IP, бэкапы).

- backend (server.js, worker.js):
  - каталог NOTIFY_TYPES с метаданными и уровнями
  - таблицы notifications и notification_reads в db/init.sql и db/migration.sql
  - SSE-стрим GET /api/notifications/stream через Redis pub/sub с in-memory fallback
  - REST API: список, счётчик непрочитанных, отметка о прочтении, удаление, очистка
  - настройки уведомлений в settings (notify_enabled, notify_retention_days, notify_<тип>)
  - автоматическая очистка старых уведомлений по расписанию
- frontend:
  - колокольчик со счётчиком непрочитанных в шапке (admin.js)
  - страница списка уведомлений public/notifications.html и public/js/notifications.js
  - секция настроек уведомлений в public/settings.html и public/js/settings.js
  - стили для уведомлений в public/admin.css
- тесты и документация:
  - добавлены проверки в api.smoketest.js
  - обновлены README.md и AGENTS.md

db/init.sql

@@ -252,3 +252,51 @@ CREATE TABLE IF NOT EXISTS audit_log (
 );
 
 CREATE INDEX IF NOT EXISTS idx_audit_log_created_at ON audit_log(created_at DESC);
+
+CREATE TABLE IF NOT EXISTS notifications (
+  id SERIAL PRIMARY KEY,
+  type VARCHAR(50) NOT NULL,
+  level VARCHAR(20) NOT NULL DEFAULT 'info',
+  title VARCHAR(200) NOT NULL,
+  body TEXT,
+  link VARCHAR(255),
+  target JSONB,
+  admin_only BOOLEAN NOT NULL DEFAULT false,
+  branch_id INT REFERENCES branches(id) ON DELETE SET NULL,
+  created_at TIMESTAMPTZ DEFAULT now()
+);
+
+CREATE INDEX IF NOT EXISTS idx_notifications_created_at ON notifications(created_at DESC);
+CREATE INDEX IF NOT EXISTS idx_notifications_branch_id ON notifications(branch_id);
+
+CREATE TABLE IF NOT EXISTS notification_reads (
+  user_id INT NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+  notification_id INT NOT NULL REFERENCES notifications(id) ON DELETE CASCADE,
+  read_at TIMESTAMPTZ DEFAULT now(),
+  PRIMARY KEY (user_id, notification_id)
+);
+
+CREATE INDEX IF NOT EXISTS idx_notification_reads_user ON notification_reads(user_id);
+
+INSERT INTO settings (key, value) VALUES ('notify_enabled', 'true')
+ON CONFLICT (key) DO NOTHING;
+INSERT INTO settings (key, value) VALUES ('notify_retention_days', '30')
+ON CONFLICT (key) DO NOTHING;
+INSERT INTO settings (key, value) VALUES ('notify_entry_new', 'true')
+ON CONFLICT (key) DO NOTHING;
+INSERT INTO settings (key, value) VALUES ('notify_entry_ai_corrected', 'false')
+ON CONFLICT (key) DO NOTHING;
+INSERT INTO settings (key, value) VALUES ('notify_entry_ai_error', 'true')
+ON CONFLICT (key) DO NOTHING;
+INSERT INTO settings (key, value) VALUES ('notify_photo_job_done', 'true')
+ON CONFLICT (key) DO NOTHING;
+INSERT INTO settings (key, value) VALUES ('notify_photo_job_error', 'true')
+ON CONFLICT (key) DO NOTHING;
+INSERT INTO settings (key, value) VALUES ('notify_ip_ban', 'true')
+ON CONFLICT (key) DO NOTHING;
+INSERT INTO settings (key, value) VALUES ('notify_backup_restore', 'true')
+ON CONFLICT (key) DO NOTHING;
+INSERT INTO settings (key, value) VALUES ('notify_backup_create', 'false')
+ON CONFLICT (key) DO NOTHING;
+INSERT INTO settings (key, value) VALUES ('notify_system_test', 'true')
+ON CONFLICT (key) DO NOTHING;

db/migration.sql

@@ -258,3 +258,40 @@ CREATE TABLE IF NOT EXISTS student_photos (
 );
 
 CREATE INDEX IF NOT EXISTS idx_student_photos_student_id ON student_photos(student_id);
+
+CREATE TABLE IF NOT EXISTS notifications (
+  id SERIAL PRIMARY KEY,
+  type VARCHAR(50) NOT NULL,
+  level VARCHAR(20) NOT NULL DEFAULT 'info',
+  title VARCHAR(200) NOT NULL,
+  body TEXT,
+  link VARCHAR(255),
+  target JSONB,
+  admin_only BOOLEAN NOT NULL DEFAULT false,
+  branch_id INT REFERENCES branches(id) ON DELETE SET NULL,
+  created_at TIMESTAMPTZ DEFAULT now()
+);
+
+CREATE INDEX IF NOT EXISTS idx_notifications_created_at ON notifications(created_at DESC);
+CREATE INDEX IF NOT EXISTS idx_notifications_branch_id ON notifications(branch_id);
+
+CREATE TABLE IF NOT EXISTS notification_reads (
+  user_id INT NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+  notification_id INT NOT NULL REFERENCES notifications(id) ON DELETE CASCADE,
+  read_at TIMESTAMPTZ DEFAULT now(),
+  PRIMARY KEY (user_id, notification_id)
+);
+
+CREATE INDEX IF NOT EXISTS idx_notification_reads_user ON notification_reads(user_id);
+
+INSERT INTO settings (key, value) VALUES ('notify_enabled', 'true') ON CONFLICT (key) DO NOTHING;
+INSERT INTO settings (key, value) VALUES ('notify_retention_days', '30') ON CONFLICT (key) DO NOTHING;
+INSERT INTO settings (key, value) VALUES ('notify_entry_new', 'true') ON CONFLICT (key) DO NOTHING;
+INSERT INTO settings (key, value) VALUES ('notify_entry_ai_corrected', 'false') ON CONFLICT (key) DO NOTHING;
+INSERT INTO settings (key, value) VALUES ('notify_entry_ai_error', 'true') ON CONFLICT (key) DO NOTHING;
+INSERT INTO settings (key, value) VALUES ('notify_photo_job_done', 'true') ON CONFLICT (key) DO NOTHING;
+INSERT INTO settings (key, value) VALUES ('notify_photo_job_error', 'true') ON CONFLICT (key) DO NOTHING;
+INSERT INTO settings (key, value) VALUES ('notify_ip_ban', 'true') ON CONFLICT (key) DO NOTHING;
+INSERT INTO settings (key, value) VALUES ('notify_backup_restore', 'true') ON CONFLICT (key) DO NOTHING;
+INSERT INTO settings (key, value) VALUES ('notify_backup_create', 'false') ON CONFLICT (key) DO NOTHING;
+INSERT INTO settings (key, value) VALUES ('notify_system_test', 'true') ON CONFLICT (key) DO NOTHING;