feat: update CMS service handlers and main application logic.

services/lms-service/migrations/20231219000003_users_table.sql

@@ -0,0 +1,12 @@
+-- Create users table for Students
+CREATE TABLE IF NOT EXISTS users (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    email TEXT UNIQUE NOT NULL,
+    password_hash TEXT NOT NULL,
+    full_name TEXT NOT NULL,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+-- Note: Enrollments already exist and use user_id. 
+-- We should ideally link them now.
+ALTER TABLE enrollments ADD CONSTRAINT fk_user FOREIGN KEY (user_id) REFERENCES users(id);