feat: update CMS service handlers and main application logic.

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

@@ -0,0 +1,13 @@
+-- Create users table for Instructors
+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(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+-- Add instructor_id foreign key constraint to courses if not already applied
+-- (In the initial schema it was just a UUID, let's make it formal if possible)
+-- ALTER TABLE courses ADD CONSTRAINT fk_instructor FOREIGN KEY (instructor_id) REFERENCES users(id);