batch add students: add optional group selection in batch modal

db/init.sql

@@ -0,0 +1,45 @@
+CREATE TABLE IF NOT EXISTS groups (
+  id SERIAL PRIMARY KEY,
+  name VARCHAR(100) NOT NULL UNIQUE,
+  created_at TIMESTAMPTZ DEFAULT now()
+);
+
+CREATE TABLE IF NOT EXISTS students (
+  id SERIAL PRIMARY KEY,
+  name VARCHAR(150) NOT NULL UNIQUE,
+  group_id INT REFERENCES groups(id),
+  created_at TIMESTAMPTZ DEFAULT now()
+);
+
+CREATE TABLE IF NOT EXISTS entries (
+  id SERIAL PRIMARY KEY,
+  student_name VARCHAR(150) NOT NULL,
+  group_id INT NOT NULL REFERENCES groups(id),
+  description TEXT NOT NULL,
+  photo_path VARCHAR(255),
+  created_at TIMESTAMPTZ DEFAULT now()
+);
+
+CREATE TABLE IF NOT EXISTS settings (
+  key TEXT PRIMARY KEY,
+  value TEXT
+);
+
+INSERT INTO settings (key, value) VALUES ('spam_interval_min', '30')
+ON CONFLICT (key) DO NOTHING;
+
+CREATE TABLE IF NOT EXISTS share_links (
+  id SERIAL PRIMARY KEY,
+  token VARCHAR(40) UNIQUE NOT NULL,
+  name VARCHAR(200) NOT NULL,
+  group_id INT REFERENCES groups(id),
+  date_from DATE,
+  date_to DATE,
+  created_at TIMESTAMPTZ DEFAULT now()
+);
+
+INSERT INTO groups (name) VALUES
+  ('Beginner'),
+  ('Intermediate'),
+  ('Advanced')
+ON CONFLICT (name) DO NOTHING;